The FXT90 is the most intimate of all those - the 'analytical' IEMs tend to sound wide and spacious, and all of them are different in signature from the FXT90. The FXT90 would actually make a nice compliment to an accuracy-oriented IEM. The sets you're considering are about on-par IMO so if you don't have more specific requirements just try whichever one you can get the best deal on and go from there. It would probably be the Brainwavz B2 or R-50 at ~$120 new.
Hmmm, very good insight, thank you. How much price increase are we talking for an upgrade that would be a good soundstage with that kind of intimate feel the FXT90s give? Any recommendations along those lines?