Oh, a really tough one. I can rule out a digital anything as I still have no love for them but do have a really nice DSLR. I've always had a hankering for a Hassey but considering the going price for used ones vs the cost for a Bronica ETRS or SQ, both that have excellent lenses just does not make me want to open the wallet. Yes, if I could find a bargain, I'd jump.
I have several vintage so not thrill, also while a Leica could be in the short list, after all the years when I could have bought 1, they never seemd to get me to spring; I preferred the feel and size of my Leicaq CL in the final analysis.
What's that leave? I recently pulled out my Rolleiflex and started pulling the system back together and fell in love all over again. It fell out favor as I built up my Bronica system. I am fairly sure that once my medical issues are put to rest, another Rolleiflex and more accessories are #1 on my list. It seems in the final analysis to be probably the best format and design of any including a rangefinder, slr, etc. The Rollei is quite light, the square format while not the optimum for many does not have the vertical/horizontal issue of either the 645 or 35mm. It can yield a 6x6 or crop easily to a 645. The accesories while not cheap make it a fairly complete system camera. Even with the 75mm.f3.5 lens, it can be shot at 1/30th of a second with no camera shake. At that speed most cameras require a tripod. Yes, there are other TLR cameras out there worth considering but other than the Yashica Mat none of them seem to have a chassis nearly as decent.