I had this dilemma a while back on forward or reverse rotation. I came accross a good deal on a 6' Kuhn forward rotation tiller and bought it. Some of the things that I was told when making my decision were:
Time or money? The reverse does do a nicer job but since I am at a marginal on the power I need to make two passes anyway. If I go slow it will be total powder. I have some more time than money to do the two passes, the reverse tiller was about $1,500 more and I do not use the tiller that much.
If you are going to do many acres of tilling or as a side job I would consider the reverse tiller. Otherwise save some $$$ and spend a bit more time on the tractor.
Consider power, like I said earlier I am marginal on the power, for forward tines, so with a reverse tiller I may have to make two passes anyway.
Also consider the soil conditions, I have hard nasty clay, some have nice soft sandy loam and some have a gravel pit. YOUR soil conditions will be a big determination on how big to buy and which one to buy.
steve