I like the TT Pro series and the Magnum XL series. The extra $5 or so to get a .46 instead of a .40 is usually a good idea, as it gives you the ability to pull your second plane through aerobatics better.

I've found very little difference in the O.S. FX and the TT Pro series as far as power, ease of adjustment and reliability.

It takes a LONG time for me to determing engine longevity. I've got a .25 from the mid 1980's which has logged at least 1000 flights (thats about 300 to 400 hours of operation) and still gives more power than a .40 LA. My dead engines broke on impact... not from wearing out.