The Mamiya 645 Pro TL is perhaps my most high-end/professional camera except perhaps my Nagaoka 4x5. It's a medium format SLR system that uses interchangeable film backs, viewfinders, winders, and other accessories on a squarish body, similar to the Hasselblad and Bronica systems. It is smaller than Mamiya's RB/RZ 67, with an image size of 6x4.5 cm. The negative size is ideal for someone coming from 35mm because it's a similar aspect ratio and you get a good number of exposures on a roll of 120 film (16). Since this model also has an on board light meter (and a pretty good one, with both an averaging and spot metering setting) and aperature priority automatic exposure, it is both fast and convenient to use compared to many of my older cameras. The Pro TL was the last model of Mamiya 645, manufactured through 2006, so this is also most likely the newest analog camera I own with the exception of a few low end point and shoots I've thrifted over the years.
My 645 came with a bunch of accessories, including the power winder grip which is excellent but which I tend not to use since it adds a lot of weight. The nice thing about a camera like this is that it has interchangeable film backs/magazines, so you can switch what type of film you're using mid-roll.