I will be installing a few r-panels this week. For the overlap should I use seam tape, caulk, or both.

If caulk what kind / brand?

I have some experience but not a ton. Maybe someone who does it all the time will chime in. I say seam tape. Put it on, pull the backing tape, apply next panel and screw it down. It's really sticky stuff,

The guys who built my shop used caulk. They said it seals better and doesn't degrade like the seam tape can overtime.

I prefer butyl tape. It's easier to work with, I think it seals better for its purpose. That said, If you do the install properly, you shouldn't even need it. I Leave it out completely when doing repairs on personal property with non critical areas and I have yet to have a panel so much as seep during the windiest and heaviest storms. I don't recommend that, of course. Sealant is a backup. Neither product should degrade to a degree as to fail over the life of that panel, assuming it's not exposed to UV.

If you had ever disassembled a panel with caulk or tape, you wouldn't be worried about how it holds up. Lol.

Most leaks I see aren't from seams. They are from not following manufacturer spec on fastening and/or driving the fastener in with an impact that smashes and destroys the rubber seal like they are trying to anchor the Titanic to a dock. It's a panel. Today's fasteners are pretty forgiving on this, so just be cool with the impact and you're gonna be fine.