Woodworking

If you have several tools on hand, just try each of them out on it and see which you like best. Don't overthink it.

Aside from that, in general a belt sander tends to be a more agressive tool than an orbital sander. You might use the former first, then switch to the latter for the final smoothing.

I would use a seven inch disc on a large angle grinder. It's super aggressive, def will be the fastest. A bit hard to control, and easy to have it dig in, so practice where you can't see it. Your arms will feel the burn after.