Really depends on the use. If it's strictly for longer than 150 yards, a 10x+ fixed is perfectly fine. You generally get a little more rugged scope and more quality out of a fixed. If you're planning on multiple roles for a rifle, variable is the way to go. I would not want to find a sprung buck at 25 yds with a 10x.

You can also look at a 4x/6x fixed. That will get you to a very respectable range, but it's very subjective. You need to try a 6x at 400 yards and see if you're OK with it.