can't speak to erewards cause I stopped doing their surveys for a long while as I felt the payoff wasn't worth the time required. However, I recently decided to start participating again.

emiles is quick but the payoff per email is only @10-20 miles. still, it only takes a few seconds and iirc I score close to 2000 miles/year.

i'm new with hotspex and don't get that many surveys from them but since it helped top of my Priority Club rewards account and helped reach platinum I don't seem to mind participating even though each survey can take @10-15 mins.

iirc, the SPAM Forum has threads on the pros/cons of each program and as always YMMV.

good luck