Personally I really like TT and OS engines. They both are easy to adjust for good running and both put out good power. To me I don't have time to be bothered with ST engines. I find them way too finicky to get to run properly. They have decent power when you do get them to run, but no more than other engines of the same size. I have also seen a lot of the throttle barrels suddenly jam on ST engines. I also have a World Models Tiger Shark 75 and a Tower Hobbies 75. Both of these have also given me very good performance. As far as tank size is concerened I use 16 0z. tanks for my 60 and 75 engines. A 12 oz. tank will probably only be good for about 8 minutes flight time so I would go for a 14 oz. as a minimum size. Normal flight times are considered to be 10 minutes flying time after takeoff, and then some spare fuel for landing and a bit extra in case you have to go around again. [8D]