I like the kayfun and the russian too (don't own them, but I've tried others') and I'll probably pick one up at some point, but I like having easier access to the coil for adjustments. Roonies, if you've recoiled protank heads (or similar) before, you'd be fine starting with the russian, but if you've never built a coil before, you might prefer having a top coil rba to start off with... with the bottom coil RBAs, you have to disassemble it to get down to the coil, so making adjustments is a little more fiddly. With a top coil rba, all you have to do is pull the top cap off to get to the coil.
Thanks for all the input guys! I've built countless protank and evod heads....started on vivi nova rebuilds so I'm comfortable with those. I just want easy and something I don't have to redo every other day. I figured this is the next logical step, even though I never really pictured myself doing the RBA's. I guess my quest to learn new things and love of gadgets, along with that search for the perfect vape, is driving me at this point.