Associate
I'd suggest going Mech although that's because I dislike bio TvZ. Most pros are using Bio+Mine and only going siege tanks if completely necessary.
Ultras are so strong now you have to play really well against them to win on even upgrades. I'd suggest Mines+Marauders, you can't shun that 125 damage even if it doesn't hit the Ultra and takes out 15-20lings XD
I would suggest you still open with Hellion/Banshee if you're good enough with it. A round of WMs after the first Hellions make roach pushes weaker and easier for a single Banshee to clean up.
I've never had much luck with mech. What's your typical mid-game composition? How do you put on aggression and when do you push and expand?