A friend of mine have the latest 80MP Phase One. He made some shots in the Pyrenees this fall, which I saw in high quality 1mx1.5m prints. Incredible dynamics, resolution, color, the lot.
I agree with Eldar Sanj, if you want the best possible IQ, Phase One 645 with the IQ280 Digital Back & perhaps the Schneider 28f/4.5 LS if your using Flash, or the 28f/4.5 AF Phase One Lens if no Flash. Schnieder also make amazingly good Tilt shift Lenses, the new 50 TS Super Angulon I've tried and it's superb.
Problem may be wether or not you can Rent the gear where you are, if in the US I wouldn't see an issue, but because this gear is sooooo expensive it's difficult to Rent in most Countries.
I've toyed with the idea of the Phase one for some time, but you need to be seriously into Landscape or Studio to step up to the cost of this gear. The Images that come out of the IQ280 Back are just amazingly good, but @ 80MP you pay for it.