Of the ones I've used so far:
Boge: standard filler type cartomizer. The polyfill material is formed around the heating wire, similar to many other cartomizers like the original KR8's. Available in regular and larger sizes, and different resistances. Easy to fill, especially the "soft cap" versions. Can be filled either by taking off the cap and dripping liquid onto the polyfill, or using the "condom method". Must be kept wet to avoid burning the polyfill material.
CE-2: made by Microcig, and completely different to the Boge cartomizers. Liquid is held in a
tank that sits under the heating coil/ceramic cup, and is fed to the coil
through a long fibre wick. Filling is by syringe only (unless modded). The R4 is the latest version that supposedly has solved some issues with earlier designs.
Joye 510: another design that departs from the traditional cartomizer. In this case a horizontally mounted heating coil sits at the bottom. The liquid is held in filler material that sits above the coil. Its almost like a regular Joye 510 atty and cartridge in a single unit. The body of this carto is plastic, and filling is by syringe only (piercing the filler hole on the first use needs a sharp needle).
There are others like Bauway makes 510 cartomizers that I think are similar in design to the Boge's.
As far as price goes, there doesn't seem to be a huge difference between any of them. My own take on the performance is that E2's are the hardest hitting, in terms of
throat hit and vapour production, but unfortunately are variable in how they perform out the box - some don't wick very well (and some are modified by users to solve this issue), some seem to take a while to break in, and the syringe filling is a pain. They last for many refills. The Joye 510 ones seem to work very nicely, with no wicking issues in my experience so far. Lots of vapour produced, and it's mellower than the E2's IMO. Flavour comes through very well. But the need to refill with a syringe is a disadvantage. The Boge are easiest to use, reliable, and perform quite well. The standard resistance ones are adequate on a regular battery but no more, but they are very good on a 5v passthrough. The low resistance (2 ohm) ones will give a lot of vapour at 3.7v.