STT is all that i have used...and love it. I would try others to get more days but not alot of options for me.
I've worked with Boston Moto for the past 2 years, and have experienced them both as a customer and an employee. Great organization and gets right to the meat and potatos for experienced track riders while providing great instruction and eases the overwhelment for first time track riders. I also rode with Cornerspeed early this spring. Looking to ride with STT too.
NESBA is great. I also like that Mid Ohio is doing their own stuff now. They actually listen to what the customer wants rather than talking to you like you owe them.
I have used nesba, STT and absolute here in the north east. All three are quality organizations in my opinion. it really just comes down to what dates each one is doing and when trying to figure out when i can go.
On the west coast here, and yes, Trackdaz is one of the top org's i like to ride with. next would be trackxperience, fastrackriders, ti2tt, and motoyard. they're all great!