Feet are always gonna be number one. That's just something that's gonna remain the same for the remainder of time when it comes to tickling. Feet always being a hit does cause producers to usually make sure they're a big part of their content. Which I can't knock them for because at the end of the day, the goal is to make sure your content sells. But as a belly fan myself who has been here for a while, I can honestly say that it's gotten a lot better over time. I joined TMF in 2010, and belly stuff then was so rare that you usually had to specifically suggest that it be included if you wanted any chance of of seeing it. Like if a producer posted a preview clip here, you had to leave a reply asking if they'd consider doing belly tickling the next time they had a shoot. Some producers did take suggestions. And some didn't. It was really just leaving a reply and hoping for the best. But as I said, over the years it's gotten a lot better as more producers are trying to include all kinds of tickling.
Here are some stores that do a really good job at incorporating belly content currently.
Tickled Pink
The BK Tickler
BC Tickle and Fetish
TicklingIsFun
Girls Will Be Girls Club
Simply Tickling
The last two have patreons, and they do take requests. I support them both and have suggested that they include more belly stuff. Both have.