OS Tiger = Super Tigre?

SK Engines are distributed by KangkeUSA. They have a good reputation as solid performers and Kangke can be contacted for spare parts and warranty support if needed at http://www.kangkeusa.com.

Super Tigre engines are very strong runners, and they are supported by Hobby Services here in North America. Hobby Services is Hobbico's service and warranty arm, and they're the same folks who provide service and warranty support for O.S. Max engines.

Any of the three will fly the Alpha .60 very well. If you have your choice of the three, however, you should take the O.S. Max engine for the simple reason that it will have a higher resale/trade value down the road.