With respect to the other correspondents insights, I would like to add this:
How do you see your TLR as a picture-making machine? Are you going to use it on a day-to-day basis? Are you going to use it as your exclusive camera?
It helps to step back and see how Rollei defined the rollfilm TLR: it was supposed to be a simple, no-nonsense, standalone camera: a Rollei and a roll of film, you are in business, being able to make effective pictures with the least fuss. You are of course limited by just one lens, but there again you will learn to "see" like a Rollei, and make the most out of it; after all, more than a generation of photographers had no problem with that, and nearly all the similar cameras followed the same philosophy, be it Minolta or Yashica, or for that matter, every maker from Aires to Zenobia!
Mamiya took a different approach and made it into a "system camera": you attack the basic body from every direction with lenses, finders, accessories... so as to custom-build a camera for any particular job. Very flexible, but it can get complicated as well.
For me as one who uses formats from subminiature to LF, I do not really need the flexibility of a Mamiya C-series. I use Rolleis, simply because they are simple, effective; they bring in the goods, and their limitations make me more careful so as to make every picture counts.
If you need a "system" camera, your only choice would be between the various Mamiya C-series models. But if you don't, the choice would be much much wider. As I see you are in my old country, it might be an idea if you can find a Microflex with Prontor shutter, by the late lamented firm of MPP based in Kingston-on-Thames. But regarding Rolleis, I would recommend a Rolleiflex made after 1954, or if you are more inclined towards European products, a late model Ikoflex with Tessar lens would also be quite satisfactory too.