mongoose vs mongodb (nodejs modules/extensions), which better? and why?

Mongoose is higher level and uses the MongoDB driver (it's a dependency, check the package.json), so you'll be using that either way given those options. The question you should be asking yourself is, "Do I want to use the raw driver, or do I need an object-document modeling tool?" If you're looking for an object modeling (ODM, a counterpart to ORMs from the SQL world) tool to skip some lower level work, you want Mongoose.

If you want a driver, because you intend to break a lot of rules that an ODM might enforce, go with MongoDB. If you want a fast driver, and can live with some missing features, give Mongolian DeadBeef a try: https://github.com/marcello3d/node-mongolian

Mongoose is, by far, the most popular. I use it, and have not used others. So I can't speak about the others, but I can tell you my gripes with Mongoose.

• Difficult / poor documentation
• Models are used. And they define structure for your documents. Yet this seems odd for Mongo where one of its advantages is that you can throw in a column (err, attribute?) or simply not add one.
• Models are case sensitive - Myself and other devs I work with have had issues where the case of the collection name that the model is defined with can cause it to not save anything, w/o error. We have found that using all lowercase names works best. E.g. instead of doing something like mongooseInstace.model('MyCollection', { "_id": Number, "xyz": String }) it's better to do (even though the collection name is really MyCollection): mongooseInstace.model('mycollection', { "_id": Number, "xyz": String })

But honestly, it's really useful. The biggest issue is the documentation. It's there, but it's dry and hard to find what you need. It could use better explanations and more examples. But once you get past these things it works really really well.