Stealth tanks and excellent for sneaking in to place a nuke. Especially during a flame tank rush, which typically distracts the enemy enough to sneak around behind a building and place a nuke then sit on it with the tank until it's ready to blow.

What I could really do without would be snipers. Compared to buying a vehicle or participating in APV runs or repairing buildings, I don't think they contribute a whole lot to the team. In one game, the other team had 5 or 6 snipers and it was extremely annoying but they never got much more than simply a lot of kills.

As for buggies and the advanced guard tower.. I've managed to rush a buggy in and get close enough to place a nuke on a building. A humvee against the obelisk is tougher, tough, since it hits a lot harder and rarely misses.

All of that said, I usually prefer medium tanks when playing GDI. They are fast enough to move out of incoming fire but still powerful enough to take out incoming vehicles before they can C4 your buildings. Still, basic common sense has to be present. Things like firing ahead of moving vehicles and don't sit still while the artillery pounds you.