As with most questions of this type there are many choices that will work. The overall weight of the plane with all items installed will have an effect. Since the Super Tigre and OS both use the same case for the 60 and the 90 size engines weight will be all but the same. The Tigers are on sale currently at Tower so if the budget gets invovled it may be a little less. The OS may produce a little more power since the design is a newer one (ST is a ringed engine and the OS is ABC type).

The 90 will give you better vertical and better down line braking (from the larger prop disc) so that would be my choice. As far as brand it's like arguing Ford vs Chevy. Go with what you are comfortable with. Good luck!

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