What method of scope doping do you plan on using for shooting to 800 yards, ie a BDC reticle design to approximate bullet drop at distance, BDC with consistent change in subtension hash marks (like 1/2 mil or 2 MOA), or dialing? Do you want turrets designations to match reticle ( I would suggest that you do)? Is weight a concern? What about focal plane? Target turrets?
I would start by answering these questions then start looking for scopes. Once you start narrowing down features the list usually shrinks to a manageable one.
Some thoughts.
It doesn't take much effort to find a scope with good enough glass for anything you might need in the field. I tend to look first at durability and repeatability (especially if I am going to be using the turrets a lot for adjusting for distance).
I would also look at CS as an important factor. I have been very lucky and have only had a couple scope failures on all of my rifles, I attribute much of this to the rings I use and how I mount the scope, but if you need customer service it is nice to have a good company that can take care of you efficiently.
This is somewhat personal preference but if you are thinking about looking at using a BDC style reticle then I would strongly consider you look at the ones that use consistent subtension hashmarks over ones that try to match varying bullet BC's. I think the benefits are great once you get used to using this kind of reticle.
Since this is a big game scope I would suggest you don't get too caught up in the high mag power game. 10x is plenty of power to make very accurate shots on big game at 800 yards. Often times guys get burnt by having too high of a mag on the low end and end up missing close up shots because they can't find their target in the scope quickly enough. I would say 3-4 is good on the low end and I even like 2.5's. I rarely go over 14x on the top end. I don't like the perception of a more shaky view the higher mags provide and I often get mirage issues above this which completely defeats the purpose. Also, staying around 10x and you can get by without a AO which saves weight and makes for a more durable scope, nice features on a big game gun in many situations.
I am slowly transitioning more and more of my scopes to FFP as I get used to the benefits they offer. As scope makers continue to add features and better technologies we are going to have better and better options for hunting purposes. If you go FFP I like to keep the power range at 3-4x as I don't seem to have issues with reticles thickness being too much or too little for varying terrain changes. Reticle design matters here too. Also, if you choose a SFP scope try and figure out what power mag you are going to be most comfortable with and make sure the subtension size fits your needs at that power range. I like buying scopes that have power ranges that allow me to quickly and easily keep track of changing subtension sizes when changing power. For instance a 2.5-10 scope with the subtention spacing set at 1 MOA at 10X means that they will be 2 MOA at 5x and 4 MOA at 2.5X. This gives me easy to remember and workable numbers for calculations. a 4-16 would give the same at 16X, 8x, and 4x, etc.
If you are going to dial for range then turret design and consistency is paramount. I would be more inclined to spend the big bucks here as I have lost count of how many scopes I have seen that don't adjust the correct amount per click and/or also change click amount as one moves from the center to the end of a turrets adjustment range. Yes even many of the big boys! I think this is one of the reasons NF is so popular with the die hard long rangers that dial. Consistent and repeatable turrets are the norm for NF.
Hope this helps.
