Stripping/Sanding doors

I came across some old interior doors I would like to try to refinish(paint). I tested one for lead paint with a test kit and it was negative. I’ll probably send some chips to the lab to confirm, but I’ve found the tests to be pretty reliable, so assuming the doors are lead free, would it be better to sand or strip the wood? I tried some citristrip, but it’s really not getting the job done, and it will use a huge amount of citristrip to get the job done. I’m considering making a steam box and steaming them or sanding them off with a sander. Which do you think will be a better experience for a DIYer?

Thanks!