I understand completely. It's very confusing and frustrating trying to enter the audiophile world. There's many claims that X is far better than Y but in reality it's not, it's just preference. You could get lost for hours trying to figure out the ideal headphone, but really if you're new you'll be satisfied with almost anything that's well regarded around here. I owned the RE0 for a while and I never liked them. I never enjoyed music on them, they were too analytical. By this I mean they made me think more about the quality of the recording than enjoying the music. They are very clear and sound great, but the build quality is iffy and the bass is lacking very much. They are good headphones, but not good for everything. Classical, yes. Dubstep, no.
The Betas are my favorite IEM under $100 that I've heard. They have an outstanding price to sound quality ratio that I find unmatched. They work well for everything in my opinion, but aren't ideal for things like classical. They do have enough bass to satisfy dubstep fans though, no doubt. The build quality is really iffy on these though, they've held up fine the past 2 weeks with them of using them roughly an hour a day at least to and from work, but I don't think they'd handle a lot of abuse.
The Tridents have a great sound to price ratio and much better build quality than the Betas. They sound good with almost all types of music, but sound a bit flat. I did enjoy listening to music on these though.
I hope that didn't confuse you further. One piece of advice though, pick something that sounds good to you that will best suit your needs and then enjoy them. Over time you might find them lacking in certain areas and that's how you figure out "your sound" you'll find yourself thinking, "The bass is a bit too much" so you'll find headphones with similar sound, but less bass. So just pick somewhere to start and enjoy!