My optics journey went from Bushnell MPED to Athlon Ares ETR to Apex Rival and I've settled on a Kahles K525i DLR. They all work, but I like the features of the Kahles the most (but think the Rival reticle is probably best for competition use).
High magnification is not that important. I run around 12-18x most of the time. Only ever go above 20x for sight-in. And below 10x for large panning stages. So something around 5-25x is a decent range.
For actions, as others have said, get what you feel comfortable with. I love my Bergara B-14R (stock barrel with a Tuna Can) and Deuce 2.0 (IBI barrel, no tuner) but I've talked to others that don't find the feel of these "full-size" rifles just right. CZ is very popular. Go to a match and ask to try as many as you can.
Ammo makes a huge difference. Once you've got a rifle, test as many brands and variations as you can (Tesro offers sampler packs). Once you find an ammo your gun like, try to lot-test it, and then be prepared to spend a lot on a few bricks of the good stuff.
