I think as a second plane and first 4-stroke, an O.S. is the better choice... Then when you get a little more adventurous, go with the Saito or Y.S. The O.S. is the japanese cars of R/C engines, may not be the most powerful, most sexy but they get the job done very well with as little hassle as possible. Can't go wrong! And talk about lemons, the gamble is much less with O.S. Just my 2 cents.

4-strokes I own
O.S.
Y.S.
ASP/Magnum
Saito