There are a number of threads here that discuss printers and their attributes. Look in the printer specific forums. It comes down to how deep are your pockets and how much you like to tinker. You can spend a few thousand dollars and open a box and print within 10-minutes or you and spend $800, build for a day or so, and be printing by the end of the week. Both have merits. But, the short answer is impossible to give you.

Your question is also too short because without knowing what you want to do, it's hard to suggest a printer. It's like asking, what's the best book to read. We have no idea what your budget is and what you want to print. There are printers that cost $50K that will do things that a RepRap printer will never do.

The materials are a bit simpler because there aren't really that many. But again, it depends on your end-game. ABS and PLA are the most popular but you can print the new flexible filaments and nylon is becoming popular. There are a few other exotic filaments but those are the main ones people talk about here.

Here's what I suggest, do a search for 3d printers and then go to each of the manufacturers sites and read about their products. It will take a few hours (or days) and what will happen is that you'll begin to pick up the terminology and the different aspects of the various configurations. You'll begin to understand that they (well, printers in the $800 to $2500 range) are pretty much the same technology just wrapped up in different ways. I get spectacular prints from my sub $800 Makerfarm Prusa i3. I'd put them up against a $2500 pre-built machine from Makerbot (don't flame me Makerbot guys....just trying to make a point...lol...). But, I had to build my Makerfarm for a day and then calibrate it for a week before I got my first good print. I'm a tinker-guy so that process thrilled me. Some people would have been completely frustrated by that process.

So in finishing, it's hard to answer your question. The opinions here about "what printer is best" will range as widely as "what is the best baseball team." You sort of have to figure that out on your own. Now, once you have narrowed it down to a few models, then come back here and ask people to compare one against the other. At that point, we can help you make a decision. But to just ask straight up, "what's the best printer, " it can't be answered until it's a little more focused.

Bottom line, just buy one and jump into one of the most rewarding things you'll ever do. Buy a bottom end one to learn on and then buy another one later to do better work with. Many people here have several printers.

And come here often for advice as there are some talented people here who live to help out in this forum.