I don't recall the OP giving us a price range, so the suggestions are all over the map. Another point I wanted to make is that camera dimensions and weight translate to portability in non-intuitive ways, probably depends on OP's style of shooting. For example:
I do not doubt that Mamiya TLRs are bigger, but they are also less dense than otherh TLRs. The Mamiya C220F that I have is bigger but not much heavier than the Rollei 3.5F, and - with my style of using a TLR with a small shoulder bag - ends up being a functional equivalent in the field. That bag, with a cell phone, keys, extra roll of film and filters ends up feeling the same regardless of which of these two cameras is in it.
I'm pointing this out because in addition to having interchangeable lenses, the Mamiya TLRs have other wonderful properties, namely their ability to shoot macro and they're a breeze to focus with: you can use either hand, and their WLF+screen combination is easier to nail focus. People who shoot Hasselblads, Rolleiflexes, and Bronicas love having discussions on which focusing screen is the best: AcuteMate, Brightscreen, Oleson, Maxwell, ground glass, fresnel, etc... Mamiya TLR users never bother, their screens are already amazing. Even the WLF magnifier is better made than other cameras I've tried: you can "zoom out" by pulling your head back and the image gets amplified more (at expense of not seeing the corners). For some reasons WLFs in other cameras don't do that as well. Basically, Mamiya TLRs are exemplars of ergonomics and precision focusing in my opinion.