fixed 6x
I'm a fan of fixed 6's and am running 3, all Leupold small bells (36mm?) Additionally, I often set my 3-9x variables at 6x when hunting, and end up shooting (read deer) game w/ that power setting as a result.
I am a believer in less is more,and in the case of a fixed power scope, I figure fewer moving parts, less to go wrong.
The longest shot, and the family record at present, is bamaboy's 260 yarder on a spike whitetail (his first buck) at a lasered 260 yds and a .243. When the celebrating was over, we found the Leupold 3-9x set at....6x. The first whitetail I ever carried to a taxidermist was shot on a powerline ROW at 210 long paces, with a $60.00 Bushnell (hey it was a while ago) fixed 6x. And to prove the point, my longest shot on a deer was at 225 paces and a fixed 4x. The point being that 6x will provide plenty of magnification for reasonable longer shots on deer size game.
I have not experieced a 6x being to much scope (magnification) in the woods or brush either. In fact, the 6x seems a bit better at picking holes through the woodys, and counting points on a rack (in a QDM program) than the old traditional fixed 2.5, 2.75 and 4x's that I was raised on.
I think that the advice of skipping the see thru mounts is sound.
Good scopes are considerable more reliable than they were in years gone by, and the need for a quick switch to irons to make a shot due to a failed scope is a rare thing these days, if you buy decent scopes.
Even good copes will fail though on occasion, and if you just insist on some type of backup irons, a viable alternative is a quality set of detachable rings and a rifle w/ factory irons, or possibly a fixed factory front and detachable rear peep that attaches to the rear base once the scope is removed using the detaching rings. But needing an instantly available back up set of irons for deer caliber sporter because of a failed scope is a rare anymore.
My Dad liked the see thrus, but he was of the generation that did not yet trust a scope,and he typically did not buy quality optics. The depression syndrome dies hard. A penny saved.......
You will get a better cheek weld and gun mount, and a less arched trajectory (though not largely different, why choke the rifle) and a tidier ,less bulky package, with a lower scope mount system too.
My fixed Leupold fixed 6x are thus mounted: one on a .223 mini-Mauser, another on a 5mm Mag rimfire and the third on a Win M88 .308. If I can find a deal on a used Leu 6-42mm, the Rem 700 .270 will get one also.