If you don't care about racing with others, skip them both and purchase an FG.

FG has buggies that run on an oil/gas mix much like a weed eater. Their initial cost may be high, but it is still cheaper than a quality nitro buggy. Why? There is no expensive nitro. There are also no real tuning issues and the weather doesn't hamper the engines since the Zenoah and Solo engines don't use glow plugs because they uses spark plugs. FG is also releasing a 2WD Monster truck that has an upcoming 4WD option that dwarfs the standard 1/8th scale.

And before anyone posts their derogatory response, I also own a Traxxas T-Maxx 2.5 with a Sirio 3.0, a Mugen Sieki mbX5 with a P5, a 1/5th scale FG, a 1/4 scale gas/oil mix, and a lot of electric R/Cs. A quick trip to the Traxxas message board will also show a post by Traxxas itself regarding tuning issues and how the ambient temperature effects nitro motors. Consequently, if it's 105F I wouldn't even bother to run my nitros, but I would run my gas/oil mix or my electrics.