"Good" is a relative term. A Grasshopper is a superior Skirmisher, but a lousy sniper.
Most of our local games have a win condition of a fast unit making it to the other player's deployment edge and gathering up points there. For that, I usually pull the following:
Locust LCT-1E
Locust LCT-1S
Mercury MCY-98
Mongoose Mon-67
Jenner JR7-F
For Skirmishers, I usually look at the Wolverine 6M, but have used one of the Phoenix Hawks (PXH-1D is good), Gladiator GLD-4R, Grasshopper, or Guillotine for that role.
For a Brawler, the Thunderbolt is a favorite, and 4/5 designs will fit that role well. The TDR-5D is a little underwhelming on firepower, so not my first choice unless I just want to freak someone out. The Black Knight, Centurion, and 4G or 4P Hunchbacks also serve this role well.
For Fire Support, I usually save the Awesome as a secondary list for new players, but I sometimes use Missile Boats like the Archer personally or a Stalker to do a dual role of Fire Support and Juggernaut.
What is good will largely depend on what you "need" to play, what "holes" you need to fill in your lance, and what BV is left.