RE: Burris vs Nikon vs Leupold scopes
I have a Leupold Vari x III and Burris Sign Series both have been excellent. I know not the models you mentioned but I think either are pretty decent. For my ML's I use bushnell elites (3200 and 4200), so just to add more food for thought or fuel for the fire I would look at the 3200 elite with fast focus as well. At around 200 bucks it is a very nice scope & would do just fine on IMHO. The only knock maybe eye relief at 3" fixed, it hasn't caused me any concern on my front stuffers though. I think optically (brightness and clarity) and features it certainly looses no ground. Has lifetime warranty(almost all do now a days), rainguard, fast focus are all standard on the 3200 elite, making it probably one of the best bangs for your buck. It would be on my short list of scopes in the range you are mentioning. Nikon has always been extremely bright scopes to my eye but there reliabilty and CS was a source of concern for me thus my lack to endorse the product[:'(].
Best advice take a boo through them all and decide for yourself. Just make sure you take them out of the shop to compare, as under the shop lights the difference are mooted significantly.
Best of Luck.