Both are a blast, I prefer the crawlers to the trail rig, but there are many who disagree and swear by the their trail rigs.
For a nice start to a comp rig, try a SW2, J2-TT, BM-VII, Pimp Cane, XRC, K2-3S, TM3, Vertical Smile, Pimp Slap and there are many more.
All are great chassis w/ several different design to choose from.
For a trail rig, try a BB-51, K2-3S, K2-3L, Trail Master, MFM, and again there are several other great trail chassis to base your rig on.
In the end, both types of rigs w/ provide you w/ much enjoyment!"thumbsup"