Biggest issue is system size, and how many lenses you want with you.
My RB bag for years and years was a Tenba Air Case, sort of small-suitcase size, hard plastic frame sides and bottom wrapped in padded ballistic nylon. I think that bag is 20 years old and still functionally new - just squeaks by as a carry-on. Body, mags, 2-3 lenses, prism. Lightweight, and bonus - you can sit on it!
I'd really REALLY really suggest padded dividers vs. foam - a good case will last much longer than your equipment setup at a given time. That Tenba, for instance, gets repurposed all the time, for video shoots, film shoots, digital gigs. I have a box full of the dividers from various cases, so I can "design" a case and pack about anything I need on a gig.
I once bought a "photo-store" level aluminum case - it fell apart after the first shoot. EBay is full of these, many are total crap.
I have a Think Tank backpack and it's a very well designed piece of gear - mine's too small for an MF setup though (it does carry a good sized Panasonic "pro" video camera and accessories, tight fit!). When I go on vacation, I re-purpose it as my carry-on for a 35 or two and travel stuff - it's just a wonderful bag for all kinds of uses - one of those pieces of gear you just sort of admire for its good design.
Over the years, I've come to rely more and more on Pelican cases (and SKB, Nanuck, and other knockoffs of the standard sizes). The 1550 could be a good MF size (I have two but they're my audio case and my HDMI case, never tried the Mamiya in 'em), they're usually all over eBay used, though you may have to buy the dividers ($100ish new). Not the best for hiking, great for taking a beating and stacking in a vehicle - for the rest of your career. You can't do much better for a reasonable weight hard case - worth every penny. They really make you feel good about packing and transporting.
High quality used cases are usually good buys on eBay - they may look a little scuffed, but most Tenba, Pelican, etc - they're really tough cases.