Monks and the effectiveness of 2-handed weapons

I am just starting a Monk build in Diablo 3, and notice that a dual-wielding setup or a weapon/shield combo is far more favorable than using a Daibo, due to the ability to equip more prefixes and faster attack speed.

Are there any reasons to use a Daibo instead, besides the Spirit regeneration bonus?

I think it's a pretty general question of 2-handed weapon versus two 1-hand items (weapons or shields). With 2-handed weapons you usually get less affixes, because you're basically throwing away an item slot. 2-handed weapons tend to have a better damage (and DPS), though.

In my experience with a Monk, going with a 2-handed weapon would typically get me 10-20% more DPS, which is significant, but often not worth it if I got a great shield or a good secondary weapon.

I think that your decision should be made on a case-by-case basis, based on the specific items. I don't think it's possible to reach a general rule for 2-handed over 2 1-handed or vice versa, Monk or not.

Edit specifically regarding Monks, there is one important difference here - Spirit-generation from skills depends on attack speed only, not on damage done or any other affixes. Since dual-wielding means +15% attack speed, a dual-wielding Monk will generally generate Spirit faster than a Monk using only one weapon.

I currently have a level 53 Monk and have never found a 2H worth using

The small amount of dps you gain from using a 2H is not enough to justify losing the extra stats obtained from having a second weapon (or shield), and losing the 15% attack speed bonus you get from dual wielding. Since Monks generate Spirit with their Primary attack, the 15% attack speed gained by dual-wielding means you are gaining Spirit 15% faster

To add to that, some of the Monks abilities and runes (most notably, the Sweeping Wind ability) are based on crits, and a slower attack speed means you are critting less

Equipping a 2H weapon with The Guardian's Path passive ability, which gives you 25% extra spirit generation, seems like a bad trade to me because you are tying up one passive ability slot for 10% extra spirit generation, slower attack speed, and a drop in stats. It just isn't worth it

So unless you are built in such a way that you never run out of spirit, and find a weapon which has enough bonuses on it to make up for two weapons, stick with dual-wielding weapons (1H + Shield is another story)

I would also agree with the pros towards the Dual wield opion from the posts above, but to add to that...

I like to tank for my group. The method I am currently going with (and will probably change half way through hell mode) is HPS tanking. I go for gear that has atk speed, dex, vitality, HP on hit, and Damage converge to life. The idea here is somewhat of a HPS tanking style. This requires a balance of the previous mentioned stats, but the most important one is speed. 2H weapons would not provide me with the amount of Hits/sec that I need to make this viable. two one handed FAST weapons are what is needed in this case. Currently I am using two fist weapons, but I wish to replace them with daggers due to the inherient faster speed of the weapons at a base level 1.5 atks per second instead of 1.4 that fist have (those numbers are attacks per second, not swing timers like WoW). But I have to keep in mind that fist are usually beter itemized for monks and have to just keep my eye on the stat differences when choosing daggers over fists.

The Spirit Regeneration bonus is about the only reason I'd stick with a Daibo. If I was that desperate for damage, I would probably grab me a mallet and make sure it had extremely high amounts of +weapon damage %. However, with such a terribly melee creature, only possible way of making this work in Inferno would be insane amounts of life steal along with Serenity. Otherwise, you can forget about it.

However, Spirit Regeneration is not a bad way to go. It is actually my favorite, better than dual wielding/shield strats by far. I wouldn't try to go with the Spirit Generation on attack skills with this, however. Your attack speed is too slow to make effective use of it, espeically with dropped defensive capabilities of not having dual wield - dual life bonus nor that of a shield. Instead, stack all the Spirit Regeneration you can. You will need a lot to spam skills that need large amounts of damage to utilize, such as Wave of Light, Seven-Sided-Strike, or Lashing Tail Kick. If you were going to do a semi-ranged monk, you'll need the spirit regen to make it possible. If you get enough Spirit and mix in a little crit, you can keep a Sweeping Wind - Inner Storm going for a little extra regen, or at least until the action stops

However, my pure favorite is utilizing Tempest Rush, with either Slipstream or Bluster to help you tank some. I have Mantra of Healing - Circular Breathing tied with Sweeping Wind - Inner Storm, which is easily charged with constant pelting of the low damage 50% Weapon Damage strikes. Then, once I get this going with my 4ish regen gear, optionally with Chant of Resonance for 2 more (I don't), this is going to regen 12 Spirit a second, plus another 3 because of Guardian's Path, you can spam Tempest Rush constantly, and you could even drop some resist somewhere and not even feel it.

Pro-tip: Sweeping Wind is annoyingly hard to keep together from group to group with conventional usage, even with massive amounts of speed skills that may sap from your defensive abilities or Spirit pool, or even the 10 second duration rune. One rarely used way to keep it alive is to recast the spell, which keeps all stacks that were on the skill previously. On your typical 150 Spirit Pool without regen, it's a crazy gamble to spend 75 spirit to maybe still not hit any enemies and be forced to use Generation on Attack skills once you do arrive. With even 10 Spirit regen, you can regenerate up to 60 of that spirit back before running out of time. The skill becomes significantly easy to manage, and 3-4 extensions of the skill are possible for those incredible droughts, and you will still have some spirit before you are forced to jump in the fray.

Finally, at level 60, it should be possible to grab onto some Life Per Spirit Spent for your Daibo/Spirit Stone. If you can nab 100 LpSS overall with the Transcendence passive, which is somewhat easy, that is 1000 life regen per second simply from the cost of Tempest Rush, which is meanwhile lowering the damage you take from both the rune and the skill's inherant knockback. Tempest Rush Monk almost never gets hit by either melee hits (except elite ones) or Desecration if he's alert, leaving mostly missiles to be really worrying about. My personal skill build is as follows:

Left: Fists of Thunder - Lightning Flash: Yes, Generation attack. Highly optional, but a good choice in case you stumble and desperately need spirit, and the quick attacks of Fists of thunder allow to quickly get back out of it while gaining some dodge meanwhile.

Right: Tempest Rush - Slipstream: You want to spam this, so you're going to need it to keep you alive.

1: Serenity - Peaceful Repose: A chunk of heal and invulnerability to get you on your feet, in case you fall behind.

2: Sweeping Wind - Inner Storm: Spirit regen...

3: Mantra of Healing - Circular Breathing: More Spirit regen...

4: Mystic Ally - Air Ally - Overall a weak summon, but the damage isn't bad with a Daibo. Tank it up by tanking up your Monk (tons of Vitality and + All Resist). To go with that, it has a 10% weapon damage AOE, which appears to work regardless of attack speed, which is a boon for Daibos.

On that note, much of this strategy is spreading a lot of damage to huge groups quickly, rather than one at a time. Tempest Rush Deals 50% weapon damage, Sweeping Wind 45%, and another 10% from Air Ally. Don't underestimate that damage, nor the damage a Mystic Ally can take, especially your main weakness, missiles.

Passive 1: Transcendence

Passive 2: Guardian's Path

Passive 3: Resolve (though Chant of Resonance or Seize the Initiative are other options worth throwing around)

By the way, I use cheap gear constantly to get up difficulties in the game, and with this strat, I can solo my way into mid-Act-I Inferno, even with only around 8k DPS. You just have to make sure you get a high spirit regen/Life per Spirit Spent Daibo/Spirit Stone (Daibo with some power, maybe socket the helm for %Life), get decent crit chance on your Amulet, Gloves, and possibly Rings/Bracer/Spirit Stone, and for all armor, pound in the All Resist, Crowd Control Reduction (more optional with Serenity), Dexterity, and Vitality as much as you can, and usually enough armor will come your way to handle what is thrown your way.