Marko:

A 6x6 TLR is a great place to start. A good one will give you a big jump in negative size, and give you a chance to decide whether a waist-level finder works for you. A Mamiya C series TLR gives you the functionality of interchangeable lenses, but is larger than some other good choices (like the Yashica options).
There is even a good, if somewhat dark prism finder.

I've added an RB67 to my options in recent years, but the Mamiya C330 I've had and used since the 1970s is still a very useful option.

This was shot with a C220 a couple of years ago that I sold because I didn't think I needed as many backup cameras. Either body, plus two lenses, fits within a very nice, compact kit.