It’s really difficult to pick one or two favorites. In finishing, form generally follows function. That said, there are some finishes I will do just about anything to avoid using! If it involves my wearing a respirator, or having to follow some ridiculous seven step recipe to ensure good results, it’s not high on my list of “go-to” finishes.
For delicate, low-wear items, I like shellac. It’s beautiful and easy to apply. For other projects, wiping varnish, BLO, DO, and other rub on finishes are great (just remember not to leave your oily rags wadded up in the trash or, heaven forbid, laying in a pile of sawdust!). For food safe applications like spoons and bowls, I’ll use Crisco vegetable oil, flax seed oil, etc. The common theme in my approach, as I’m sure you’ll recognize, is if it makes me high, brain-damaged, or can create a cloud of explosive VOC’s in my shop, I don’t use it. I know lacquer and all the modern variants thereon have their place in modern woodworking – God knows I’ve used enough of them in the past. I just don’t want to use them anymore. I try to do things as “old school” as possible – for sanity and safety – hence the reason I’m ecstatic that Joshua has launched the hand tool forum for me and the rest of the net’s Luddites (I wonder what Mr. Ludd would think of all of us who are passionate about using traditional methods of woodworking while learning about it and discussing it on a computer…)
But to get back to the OP’s question…if I were restricted to only one, though, I think I’d pick a rubbed oil finish and a coat or two of paste wax. In my opinion, that’s about as simple and beautiful as wood gets.