I came from a 525i and have played with a DLR, ATACR, MK5, & S&B. Personally I like the Vortex G3 better than all of them. I think on the used market especially, it's really hard to beat for the money.
If weight is a concern, the G3 is a brick. The Leupold MK5 FOV is terrible in my opinion, glass is mediocre, and turrets are squishy, but it is a reliable optic that works for a lot of people and is probably the lightest optic you'll find in its class.