RE: what is your opinion and why?
I have a 3x9x40mm Burris Fullfield II and a Leupold VX-I in the same size. As you can probably tell from my previous posts I haven't had the best experiences with the Leupold. It's okay but not worth the money imo. I took the Leupold off my 30-06 and put the Burris on and am much happier. It's amazing how clear the Burris is. Just a great scope so far. I've only had it on for one hunting season though but so far I love it.
The Leupold I kept as a spare and ended up putting it on the Remington Genesis muzzle loader I got. It's not the worst scope I've used but it's been sent in for repair 2 times in the less than 2 years I've owned it. I bought it brand new btw. I also like the crosshairs in the Burris way more and just like the Burris way more so I'd go with that.