Both the rtr gt2 and the rtr xxxnt come with decent .15 abc pull start engines, both are very race-able trucks, and both are very solid for "bashing". only thing really that separates the two is the radio system, the losi comes with a digital jr xr2i (still an AM radio tho)
if you plan to race mostly, go to your local track and see what everyone is running, so you can get setup help, and see part availability in your area.
if you plan to bash only, look into a an older gt on ebay or from someone locally that just bought a gt2.
Flying Farmer Traction Sauce - facebook.com/FlyingFarmerRC