Okay, I will bite. I have notoriously not been a Burris fan, but every now and then, they have a scope of great value, and I think the 3-18 XTR3 is one of those scopes. Furthermore, you find a number of members who speak highly of that scope. Conversely, I have been a fan of the Sig Tango 6, while just about nobody else is. Sig is doing more and more with their optics and every year, they come up with something new. So, the Tango 6 is solid. The 1-6x has become quite popular as the military has adopted it, and now some are all made in the USA. Their MSR line, which is a budget scope in LPVO is like the budget Burris and Vortex line, and one heck of a value with a mount included.
Now, back to your situation. I think you will do fine with either. What I will tell you is that resale on a mid-magnification or long range Tango6 is not good, if you go to sell or trade. Burris is not that great either, but my guess is that with the popularity of the XTR3, you would not have a problem trading-up.
Mostly, I would choose based upon the reticle. I am not a fan of the SCR2, but it is a personal thing, so look at each reticle and flip a coin. If you expanded your budget a little, the Leupold Mark 5 HD in 3-18 will give you more reticle choices, and the Nightforce NX8 is a smidge more.
Commercially, we sell Burris, Leupold, Nightforce Sig and others, and if we can help you make a purchase, DM me.