A big thing to remember: "A 50mm" lens on a medium format might not be 'a 50mm'. - Don't forget that your field of view is larger with the bigger negative. So a lens that you like to use at a given distance from another format won't give you the same view on a medium format.
What do you want to Do with the camera? What do you want to photograph? How do you want your workflow to run?
Do you want to do colour negatives? Colour slides? Black and white negatives?
- Developing film yourself is easy enough, and black and white film is almost dead simple to be honest. There are a number of options for various 'day light tanks'. Personally I use Paterson tanks and reels, and load them in a simple changing bag.
Chemistry is easy to mix up. I like mixing 1L powder kits, but I may switch to 5L packs of ID11 this summer as I hope to be shooting far more film. Buying yourself a few graduated cylinders and large measuring cups is relatively inexpensive, at least compared to developing a dozen rolls of film at a lab. It can be done right on your bathroom counter. (I've been kneeling down and using my tub. Works well enough for me, and any spills or drips are easy to clean.)
But as far as cameras go: What format do you want to shoot?
6x4.5 gets you a few more shots on a roll of film, but 6x6 negatives are hard to say no to. (I also rather like the added difference from my typical digital work in 6x6, which is a nice bonus.)
But you can get cameras with some insanely wide format in the mix as well.
Then there is the question of, what kind of features do you want? Do you want auto focus? Do you want an in camera light meter? Do you want it to advance the film for you? Do you want a camera with as few features/functions and is as simple and with the fewest things to possibly break on it?
Do you want to use it mostly in a studio? Do you want to wander around with it? How heavy of a camera are you willing to deal with?
How do you feel about range finders, or Twin Lens Reflex cameras? (I rather enjoy TLRs.)
Medium format cameras have been made for decades, all tuned to different qualities and purposes. You'll have to ask yourself just what you want to do and what is important to your goals to help you narrow down your search for the perfect camera.
Canon EOS 7D | EF 28 f/1.8 | EF 85 f/1.8 | EF 70-200 f/4L | EF-S 17-55 | Sigma 150-500
Flickr: Real-Luckless