I've run both and they're both pretty good. Some people will say that the FP is better, but that's just sour grapes 'cus you can still buy a new LA and FP's are an aftermarket item.
If you go with an LA you can still easily get parts from Tower to keep it top notch.
Also, the two engines fit the same mount, so can always swap out later.
In Michigan, Ontario, and Carmichaels, the LA 25 is THE legal engine (at least of the two on your menu).