I started with a Burris E1 2-7x35mm. It was crystal clear, but just wasn't for me.
Then I tried a Weaver Extreme 1.5-4.5. It has a 30mm tube, the light gathering ability is incredible. Even with cheaper lenses, it is very very bright even in low light. The reticle has an illuminated dot in the center, for shooting in low light, so it is fast on target in bright sunlight or at dawn/dusk.
1-4ish scopes are the way to go, to be fast enough up close but allow you to see better a ways out for informal target shooting or hunting. Also, skip the 1" tubes, it's old technology, go with a 30mm tube.
Also, American Defense Manufacturing is a great source of quick detach mounts. They are equal in quality to LaRue, but with a better attachment system that does not mar your rifle, all for less $$$ and 100% made in Wisconsin.
Don't forget a set of flip up iron sights in case the scope decides to malfunction or break.