The absolute best of all time was Maximum Punishment, by the studio Tickle Intensive
Honorable mentions (if you like the sub-genres):
- Agent Bailey (FTKL)
- Double Dose of 'Lers (Tickle Abuse)
- The story of how Amazona decided to have fun with her students Leya and Tonya (Tickling in Russia). Weird script, but gorgeous 'lees and incredible reactions
- Hardcore Tickle Sisters (Czech Tickling)
I keep going back to these all the time. I think they saved me a lot of money because after seeing these, I don't feel that much like buying new ones