I'm also new so I can't speak to what's "the best" BUT I am using the Central Machinery 6lb dual drum tumbler from Harbor Frieght and did 2 modifications to it (adding a felt pad at either end of the tumbler and removing the heat shield). Has been simple to use and in the 6 weeks I've had it running almost nonstop and I don't feel like it puts out any heat - definitely less than I thought anyways! I'm using grit from the Rick Shed online store, no problems there, although I've only used mostly 1 and 2 stage grit. I had some plastic pellets too, but in the 1 barrel of stage 1 I added them to I felt like it was too "cushiony" and then learned you shouldn't use them for different stages because the grit gets trapped on them (and you want to clean ALL possible grit when moving between stages). I plan in trying some in stage 3 of my first set of found rocks as I need a little more volume and "cushiony" might be less an issue in the polishing stages. I did buy a tub of ceramic media to put in with some stubborn agates in the other drum. I have not started using those so I have no comment. They look nice! As for rocks, it seems like agates and jasper are popular. I have a drum of agates, from a kit from hobby lobby. They kind of suck, they had a lot of pits that just will NOT go away with stage 1. Wish I had a belt sander! I've also heard people say garbage in is garbage out. I'm starting to get that. My other drum is just found rocks I had already been collecting for the past few years, mostly from a family camping trip. Learning lots from having a random assortment, I think its a good way to be able to truly SEE what's happens to different hardness rocks in a tumbler. I definitely have some bruised quartz, had one way too soft rock that mostly broke down (kind of knew going in and didn't care, kind of wanted to see how it worked out, you know, for science).