I'm more of a TPB fan simply because it's the whole arc/series in one book, which I find much easier for reading and storing purposes... Plus most of the time you get all the covers included, and also extras sometimes..

Plus it's much easier to pick up one TPB instead of several individual issues, but that's just me...

When it comes to selling them, I'd say you would get back what you paid for them on eBay, and possibly more for rarer covers.. I haven't sold any of mine because I'm not running out of space or anything so don't feel the need, and even if I was running out of space I'd sell other stuff before my comics..