Well where are you going to be running? If your going to be running in your back yard then a MT(monster truck) is the way to go. If you have short grass then possibly a ST (Stadium Truck). A buggy can also runn in some longer grass then the st but not as high as a mt. Truggy is kinda like a mix between a Mt and a buggy.

For a st I would reccomend a team losi xxx-nt 2 or a team associated rc10gt.
For a mt The team losi LST2 or a savage x does ggod. A traxxas T-maxx and revo are also some good choices but there engine's are questionable.
For a buggy Ofna makes some good buggys for the 1/8th scale part.
As for a truggy I do not know as I never really owned one or driven one. But im sure that someone will chime in on the truugy part along with some other choices that will be good.