Any of those motors will be fine. The CC2200 might be too powerful/torquey for a buggy on the track. The CC2650 might be too fast unless you gear down. The RX8 2050 would probably be just right power and speed-wise.
Another option is Castle's 1512/1.5y (1800kv). Might be a tad slow on 4s depending on your gearing options, but is ready for 5s or even 6s if you choose at a later date. 5s would be the sweet spot on this motor IMO. And if geared for reasonable track speeds, should provide relatively low current, which helps efficiency and runtimes.
I love my Castle Neu MMM (1y) setup.. the 2200 as long as you are geared properly and have everything turned down in the ESC is perfect for racing against nitro buggies. I run a 8ight-e 1.0
The 1512 1800 will not be slow on 4s. Don't be afraid to use to use pinion sizes in excess of 17 teeth. On my tekin 1900 kv (pretty much the same motor), I gear 13/46 for a 80x50 foot track and nobody is faster than me on the straight. In other words, the acceleration curve from 0-30 mph is just as good, if not better than any other motor i've seen. 15/46 is dead even with nitro on a 150 foot straight. One of the greatest benefits will be the long runtimes and low motor temps. And yes, 5s and 6s is great fun!
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy
i decided to buy the MMM 2200KV for my losi buggy :)
with 4S 5000h 40C from hobby city!
Good choices
1. MBX-6 T8 1900KV, RX8 ON 4S
2. MBX-5T 1520, MMM ON 5S
3. MBX-5 ONROAD CONVERSION 1515, MMM ON 5S
4. MRX-3 ON ROAD CONVERSION 1512, MMM ON 6S
5. TEN T 2650 T8, MMP ON 3S