What engine...
If you can spend the cash, I agree with hobbsy. Get the Enya, it is far superior to the others. I have been running an Enya .40 for 15 years and it gets better every season. I must caution you to give them a good long break in. That done they last forever. It starts right up and you don't even have to touch the needle.
Max
P.S. If you choose one of the others, go for the Thunder Tiger Pro for ease of handling and power.