Having recently amassed a small collection of TLR's, and given the choices you have in front of you right now, I would recommend the Rollei. The Yashicas are reported to have hit-and-miss lens quality (though I have a Yashica D with a very nice, sharp lens). The Rollei TLR's have a nicer, more solid feel, and a brighter focusing screen (in my experience). As far as how the cameras are in actual use - they're pretty similar.

Play around with each one if they will let you and see how each one feels in your hands. Test all the shutter speeds, as these old cameras tend to get sticky shutters with old age - especially in the slower speeds, which is easier to detect by ear than the fast speeds. If you're just getting the camera to play around with, you may not want to go directly from the shop to a repairman.

If you find that TLR's are for you, then you can always look into something fancier at a later date - when the prices might be even lower than they are right now.

Just some thoughts from someone who finds two lenses better than one!

Joe