Easy the grey Etymotic triple-flange tips are by far the best.
Heres a link where you get 10 sets, http://www.amazon.com/Etymotic-Research-ER38-18-3-Flange-Replacement/dp/B006WT2AD8/ref=pd_sim_e_2
Yeah, I've heard good things about these too - they will fit the R-50s? Also, are they all one size? I know some of the others come in multipacks with different sizes.
If you like an IEM that's more on the brighter side yet still quite smooth over all the R-50 is perfect and if your wanting a warmer sound that's even smoother than the BA200 is the way to go. No matter which one you get both are an outstanding value and have top-tier sound quality.
Yeah, it sounds like I can't really go wrong either way. Keep in mind I'm coming from a Klipsch S4, so it should be a solid upgrade regardless. I'm just really looking to get away from the fatigue that the S4's bring, and get a better soundstage and instrument separation. Sounds like both the BA200 and R-50 will do the job. I just don't think I'm crazy about the flat, short cable of the BA200, or the huge splitter.