I'm still trying things out but so far I'm liking the 3m 967 Cubitron belts for heavy work. Then I'm using the 707JE belts in 120 and 220 to refine things but I think I'm going to look at other options for general 120/220 use since they don't seem to last real well. The trade off for how thin and flexible they are is that there's not a lot of abrasive there. I still really like the Gator's and usually start with the A65 and go through A30. These are my favorite belts but they're not general grinding belts, more a finish/refinement belt. I literally go A65 through A30 in ten minutes including changing belts and keeping things cool....
The two sairon belts I've used both have a bad wobble to them but seem to wear well so I'm using them on flats.
I haven't used them much but the hermes J-flex are REALLY soft and flexible. I used them on the two handles I've done with the new machine and they worked great. AVigil isn't the first to praise them and suggestions here are what prompted me to try them out. I'm not sure I'll use them on metal but I may try them for plunges, they're even more flexible than the 707JE's. They're an incredibly soft belt.
I'm using a Trizact A16 belt and the Norax X16 and X5 belts. I'm not sure which I like better yet but both seem to work great. I wasn't sure how much use I'd really have for them but I think I'll pick up the rest of the set of whichever I decide on.
For scotchbrite I've got the medium and should have started with the fine. Medium looks like around 80 grit scratches. They're shallower than that, but that's the look. Other than that, it works as advertised and I suggest including the fine/very fine version with your belt order unless you really don't like satin finishes. I think I'll probably find lots of uses for the medium other than just as a finish belt. Blending edges on other projects, cleaning up rust on old tools...
Other than that, consider this a subscribe

I'm curious what else folks suggest. I'm waiting on some 984 cubitron II's to try out and have a 977 in 36 grit to try still. Blaze is on my list, particularly since they come in a 120 grit too. I'm just waiting a bit since folks are reporting problems with the backing leaving black crud all over the platen and sometimes even the wheels. Norton's aware of it and looking into it, but I figure I'll use other stuff till they offer a solution.