For higway use or travelling GTS. For highspeed, stiffness, cargo area, stereo sound, comfort, GTS.
For convertable, open roof, wind noise, sunburn, etc. R/T.
Back end of both cars are radically different as are the looks. For parking in the garage there's not much difference except the GTS has a higher value.
Unless you're primarily concerned with looks (pick which one you like best), your best choice will be acording to what use you have for your car. I do a lot of highway driving and start each trip with 2 big suitcases and come home stuffed. R/T wouldn't even carry the suitcases.
Ted