In my amber ale I have been using Centennial for bittering and cascade for flavor and aroma. This has worked out well. But I am going to try Magnum. There seems to be rave reviews on this forum. Your right that there is a huge selection. I stay away from European hops mainly because of the expense.
For my last IPA, I used Centennial, but with my next rebrew of it, I plan to switch to Warrior, mainly because it will help put the focus on the insane amount of Citra, Mosaic and Cascade I'm adding for flavor and aroma, and dry hopping.