What are the differences between the four racial T3 Cruisers?

I've heard that Loki is the best SC when it comes to PvP, while Tengu excels at PvE, and I haven't heard that much of Legion and Proteus.

Besides the obvious racial traits such as "Amarr have armor tanks and lasers, Gallente have drones etc.", what are the main differences between the four, and why are they better at certain tasks than the ones of other races?

Long story short, what makes Tengu so good in PvE, what makes Loki so good in PvP, and what the hell are the other two made for?

In my opinion since the Heavy Missile changes, the Tengu isn't the "best" mission runner anymore. It's not "bad" since you can still fit it up with HAMs but it's a lot more balanced than it was. The Tengu is so loved because it's a true jack of all trades.

Here is a breakdown of the pros and cons of each of the strategic cruisers;

Legion (Amarr)

• the good: Highly versatile, great damage projection, can be fitted as a neuter, good tank in almost any setup, can fit HAMs, Legion armour boosts <3, probably best armour T3 for running sites
• the bad: No real EWAR or tackle benefit unlike the others (Loki webs, Proteus points, Tengu jams) limit its usefulness in PvP, bad when set up with a cloak

Loki (Minmatar)

• the good: Brings the most utility, awesome webs, can be armour or shield tanked, good with cloak subsystem if you mean to bring utility, probably most useful out of the four with capitals on field
• the bad: DPS is pretty poor

Proteus (Gallente)

• the good: Best cloaky ship while maintaining high DPS, especially with blasters, blasters > everything for close range DPS.
• the bad: Can't fill many roles, not versatile

Tengu (Caldari)

• the good: Good mission and site runner for solo play, jack of all trades
• the bad: Not got a great shield, heavy missiles are quite poor since the nerf, average DPS, doesn't really master anything