For your purposes, I'd try and find a Zeiss Conquest 3.5-10x50 with a #4 reticle. This model will even suffice for hog hunting when there is decent moonlight and won't break the bank, either. But they are not being made anymore, and Zeiss doesn't even offer the #4 as an option for some odd reason -- not even on a custom basis.
The two keys for a scope like this -- aside from the obvious of good glass and coatings -- are magnification and the ability to resolve detail under poor lighting conditions. This will take you where you need to go as far as deer are concerned.
It's another ballgame entirely for hunting by moonlight, though. You can have a "bright" 50mm Tasco, but I can assure you that under minimal moonlight, you are not going to be able to differentiate between head or tail of a dark-colored hog at 150 yards.
And while it may be no "brighter" than that Tasco, a Zeiss Diavari Victory 2.5-10x50/#4 will allow you to make that same shot with relative ease. Up until recently, I had two of those (one is finding a new home with a 24HR member in Louisiana!). They are the best I have ever tried, and while I certainly have not tried all of the high-dollar offerings, I know that this model works as intended and under the worst of lighting conditions.
Coming close to that performance is a Swarovski PV 2.5-10x56L/#4. The Z3s and Z5s (same glass, different internals) work OK for good moonlight but not when the conditions are tough.
For strong moonlight, a Zeiss Conquest, Swaro AV & Z3/Z5, Nikon Monarch, B&L 3000/Bushnell 3200 (and 4000/4200), Burris Signature & Euro and newer Leupolds from the VX2 on up along with others (given proper reticle) in that same class will do fine -- and 40mm works OK as long as the range is reasonable. But a larger objective will allow a higher power setting, which in turn allows you to see more detail for those longer shots.
But when the lighting is compromised by cloud cover or other factors, a MeoStar 4-12x40, MeoStar 3-10x50, MeoPro 4-12x50, Kahles Helia CL 3-10x50, the Diavari Victory and Swarovski PV 2.5-10x56 -- all with their respective #4s (4-a in Kahles) -- are what have worked for me. The MeoPro 4-12x50 makes the cut but doesn't quite resolve the detail as well as the others. But it WILL allow you to make shots where lesser scopes will fail you.
Two last things: One...the FFP of the Zeiss and Swaro mentioned above are definite bonuses in these conditions. And lastly: if you don't focus the reticle to your eyes, you will "lose" it in poor light as it will seem to fade away much moreso than a sharply-focused reticle.
This is really excellent information; well written,instructional, and obvious Bobby has a lot of experience with these low light scopes.
Even I understood it.
Thanks for a great post on the subject.
Makes me wish I had not passed on that 50mm Zeiss. 
