final mileage: i'm supercharged with 33's, i get ~12mpg
additional horsepower: TRD; fully upgraded expect 75 horse gain
turbo; your wallet is the limit for horseys
ease of installation: supercharger; a few hours. easy peasy.
turbo; there are no bolt-on manifolds i'm aware of. so expect to fork some cash/time out to plumb it up, plus fitting an intercooler will be time consuming. tuning it will be time consuming etc...
If you want to make more power with the TRD down the road you'll have to fork out more$$ for gauges, meth injection, fuel controller, injectors/7th, fuel pumps etc. (read: URDUSA.com, tokensolutions.com)
vehicle integrity: the charger, if kept as a low boost system will be relatively unnoticed for wear and tear. the more air you put in the hotter everything gets(in general). so it will come down to you on this one.
final cost: every penny you have and then some, regardless of choice.

you can feasibly do the trd for $3k. I don't know about the turbo, but I'd expect to see $5k go out the window.
forced induction is really great stuff, but it's also a rabbit hole. read up.
..just one mans opinion.