Slush-box tranny's are for little girly men. Strong muscular men drive manual transmissions!
With that being said- stay clear of the T5. You're still in your teens which means you
ARE going to trash through the gears! No offense- just sayin'. The T5 and even stock T56 can't take much abuse. Keeping the budget low and factoring in a reasonable amount of dependability....I would either throw-down and get the TKO, Richmond or Kiesler 5-speed or get your self a reman'd MY6, which is essentially an A883 (think BB 'Cuda) with a GM bolt pattern and input, with the exception that 4th gear is a .88 overdrive cog.
If you wimp out and swap for an auto- go with the 700-R4, the lower first gear will get you off the line quicker and help with the whole "occasional towing" thing.
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