At one time I had a lot Burris LER's. They worked great for me in a variety of shooting and hunting conditions.
I think I have had one go down on me. I didn't/don't have as many Leupold LER's, but I have had one go down on me as well.
They both have their strengths and weaknesses for my uses.
I like the Ballistic Plex reticle with the Burris. There are no reticle options for the Leupold.
I like the turrets better with the Leupold VX-3's.
Eye relief has already been mentioned. It is not an issue for me.
The Leupold has a LOT MORE internal MOA. Big plus if you are extending distance.
With Burris Signature Zee rings and the BP reticle, I can do about anything I want.
The 3-12 is limited here though.
More magnification with the 3-12 with a PA.
Each has their strengths.
Get what you want.