I've owned/raced buggies/truggy's from these companies.
AE (RC8Be,RC8.2e,RC8Te): Fragile and twitchy. Did like the Truggy better than the buggies. Great shocks.
TLR (8ight 2.0 buggy/truggy): Good cars with bad plastics. Slop develops fast. Handle rough tracks very well. Tekno conversion makes these cars better.
Mugen (Eco USA/Std): Awesome. High quality, excellent handling and durability. Needs no upgrades. Drive train lasts a long time. Chassis slap an issue.
Serpent (811be 1.0): Super high quality. Difficult to tune on rough/loose track conditions. Parts expensive.
Xray (XB9e): Excellent buggy. Easy to drive. Very high quality parts. Poor e-conversion. Parts expensive.
Hot Bodies (Ve8): Awesome. Super stable and easy to drive. Very durable. Needs a lot of upgrades, lacks tuning options and weak e-layout.