We were just at HS first week of September and even though there were no waits for any rides any where else, there was, at one point, up to an hour wait at TSM. We grabbed a FP in the morning and did it once in the afternoon.
I would have loved to do it again but waiting more than 20 minutes for a ride with 4 year olds is not something I like to do.
My twins loved Buzz and to them there really wasn't much of a difference between the two, and Buzz was also easier for them to shoot. Plus, we could ride Buzz 3 times in a row with no waits.
For older kids, TSM is probably more fun plus it is one of the only kid rides at HS.
If you get to HS early enough, you may be able to get your FP then ride right away, before the line gets along so at least you'll have 2 rides without too much of a wait.