I was thinking the Hydra and Flamethrower tanks are too much of a gimmick with only one weapon. The original tank and the Goliath heavy tank are both generally better because of their versatility. If the Hydra tank had both a rocket and a flamethrower weapon, it would be a special and versatile tank worth using.
Here's my suggestions for the tank lineup, if you're interested (feel free to ignore it):
Perseus: costs red/green science only, prereq. military 2, +100% damage bonus machine gun, faster and more agile than basic tank. Its machinegun is the same power as the basic tank and it moves faster so sometimes it may have late game use.
Basic Tank: same as current 0.15 version
Hydra: rockets, flamethrower with longer range and higher damage than player flamethrower, maybe takes its own special ammo, tank is slow-moving but fairly agile, resists explosives and fire -- maybe even give it a shotgun basic weapon to vary it further from other tanks. Shotgun also fits its style of spreading damage around.
Edit: after playing with the handheld flamethrower a bit, I decided its damage is already plenty high enough and it would probably be better to give the tank flamethrower a bigger spread radius, so it's easier to blanket large areas in fire.
Goliath: 2 cannons, gatling gun, slow and clumsy, very heavy and with high impact resistance so it can plow through worms and spawners without taking damage -- would be cool if it got a depleted uranium ammo for the gatling gun O.O
I can't wait for the 0.15 update!
