Leupold would be my suggestion.
I like the Nightforce scopes, and I do own one... but they've raised the prices to more than 2000 dollars on most models... a lot to pay.
I hope not to offend anyone who has European glass--because it's truly great, no doubt. I just think that we're living in an age where the future of Europe's economy is looking really bleak. I'd be a bit skittish of making an expensive purchase from any company based "over there" at least for the foreseeable future.
Leupold has "staying power." It's a strong American company, and they'll likely be here as long as America is here (which is another debate)...
But for magnification, you would be well served with a top magnification of 10 to 14x... it'll work very well, out to 1000 yards.
We just finished our winter "polar bear" match, and we found ourselves advising many shooters who were unable to spot their own ground strikes (when their bullets missed the targets) to DIAL DOWN the magnification, and expand the field of view. This is a very difficult thing to get folks to understand--but you really don't want more magnification than you need to quarter the target, and view it clearly. You really can have
too much magnification...
I shot my .308 in the comp, with the longest ranged target sitting at 1050 yards, and a bonus gong of 10" in diameter sitting at 1065 yards... the bonus gong was easily seen in my scope's magnification, which was 15x (Nightforce NXS 3.5-15x50).
I've used Bushnell's 10x Elite tactical for these targets as well. Ten power works just fine for quartering MOA targets. I made a 755 yard kill on a groundhog (one half MOA in width) using a Bushnell 10x Elite tactical... so it'll work.
We train long range shooters here at our SW Virginia facility, and have found over and over again that if you get the shooter to overcome the mistaken notion that he can "shoot better" with more magnification, you generally see more hits at long range.
Good luck on your choice. The Mark 4 will have good resale value, too, if you get it and decide to get something different later.
Dan