If you’re in the area this weekend, as Wade mentioned, you can see a great example of all of those engines. At the Gearup race there will be 2 strong Leopard classes, as well as the TaG class that mixes X30, Rotax and Vortex engines. If you do and have any questions Wade and I will both be in and around the Swiss Hutless tent.
I would advise starting on a Yamaha, with all due respect to Walt I wouldn’t buy a Briggs motor and hope someone else shows up with one to race against. If you’re just starting out, the Yamaha will force you to drive and learn how to corner. After a couple of years of TaG motors we went back to Yamaha Sr at Etown this year and the fields have been picking up. About 13 entries at the last race and a lot of fun.
My son started on the Yamaha, went to HPV, PRD Fireball and then X30. I absolutely love the X30. BY FAR the most reliable and lowest maintenance engines we’ve run. If you’re dead set on starting with a TaG I couldn’t recommend X30 enough. The Leopards are still the standard but they are slowly being phased out (by race promotors and IAME) and within a couple of years you’ll own a boat anchor.