I use both range finder and TLR at the moment, and used to use Hasselblad. For accurate, close up focusing. I much, much prefer range finder focusing. I find it so much easier than either relying on my eyes to see focus, or even the split screen, which are good, but I do struggle a bit with them.

For tripod work, I much prefer ground glass/SLR, not just for looking through the lens, but the convenience of looking down on the screen, not crouching to look through the finder.

So for me, carrying it around? Mamiya every time. But if I'm using a tripod 99% of the time, I'd take the Hasselblad. I will say that often range finders have more accurate framing than you'd think, and unless you *really* want to include details at the edge of the frame, accuracy may not be that important.

It's a personal choice, but I find I like both for different things, and RF and SLR each have their place.