I use a Bama 93 Race Tune, and I love it, that tune with the C&L Racer CAI makes a huge difference over stock, I have an 06 auto GT and with the 93 and C&L & 410's my car chirps 2nd-4th gears, and has chirped 5th a time or two (when the gas tank was a bit low =less weight) Bottom end is really awesome, from a standing start, if I just floor it, the car will spin the tires thru first, second and partially thru third till it hooks, from like 60 to 100 is amazing too.
I have a BlowByRacing 93 Race Tune as well, its a good tune but does not have the same seat of the pants kick that the bama 93 has, I've never used a Brenspeed or Tillman tune, but I hear they are awesome.
What are you looking to get an 86/89/91/93 tune? If you're wanting an all out tune I'd obviously go with a 91/93 Race tune (whatever the highest octane you can get in your area) and also a 91/93 Performance tune (if you find the race tune is too much) you can also get a 91/93 street tune which is a little less than the performance tune.
Personally, just from the experience I've had, I'd recommend Bama, their tunes are amazing, especially the 93 race!!!
If I were to suggest anything to you it would be to do the tune of your choice along with a C&L, Steeda etc.....CAI at the same time, you will NOT regret it.
Just my 0.01 cents.
Best of luck, let us know what you end up doing