What ever u do don't touch the 7.5 sport.
I have heard nothing good about them, unfortunately after I brought one!
Have had nothing but trouble with the engine and parts are so expensive.
Best buggy I know for value is the Sacker Pro. The basic RTR kit has all the hop-ups and is very quick!
Replacement parts are so cheap, yet the quality is very good!
Parts are identical to Kyosho and in fact are interchangeable.
This car has recently won some world champ races.
The other kits you mentioned are expensive when it comes to parts. This is an important factor as with 1/8 buggies you can have a lot of breakages which can be expensive.