I have decided on a Manfrotto MT055CXPRO4 tripod head.
But I can't decide upon a head. I am not too sure about the ball heads, think I find them finicky, I want a leveler to be on the head, that is for sure. and I guess it´s actually on the tripod head you hang a bag if you need to (important as it can blow a lot in Iceland). Why do a lot of people seem to prefer ball heads?
What heads are you using and do you recommend any special ones?
I find a ball head to be very useful for both Hassy and Rollei when using waist-level viewer. They can be very quick to level and frame with. With almost any other kind of camera (or those cameras with prisms) I find a 3-axis head more effective.
A ball head for the Hassy is much faster and easier to use than a 3-axis head. The caveat is--cheap ball heads are miserable. I've used an Arca-Swiss B1 for a long time and it still locks down as easily as the day I bought it. Arca-Swiss, RRS, FLM, Acratech, Kirk are quality brands.
Arca Swiss B1 seems optimized for a heavier camera like the Hasselblad or Rollei SL66 and works very well there. With a lightweight camera, not as much. B1's ball is elliptical, which counteracts the tendency for the camera to flop sideways when the tension is released. For a lightweight twin lens reflex, I might choose a smaller head.
Some of today's Chinese ballheads are pretty good: They seem to have discontinued it, but Vanguard used to offer a near clone of the B1 done on a smaller scale, and it works great with my mirrorless cameras. And for smaller cameras and my travel tripod, I have a Joby Ballhead X.
I like my Manfrotto 054 head - works well with my RB67 and my C330, and is easy to use with my 35mm cameras. You need to choose the one that matches your quick release needs.