My reasoning is very simple, really, but first I want to re-iterate that these are the choices specific to me and my needs, rather than general recommendations.
As a basic disclaimer, I also want to add that I got into shooting comparatively late since where I grew up you only saw guns on TV. I am not a particularly good shot and I do not have much formal training. I do have a fair amount of trigger time behind me, so I have some very specific preferences.
Long range precision scope: March 5-40x56 offers an extremely wide magnification range which saves me from needing a spotter. I like the basic reticle with a floating center dot and the feel of the turrets is the best I have seen to date. 5 mrad per turn is not optimal, but I can live with it. Tight eye relief flexibility is not a major issue for me either when long range precision shooting is involved. This scope is also a bit lighter than most of its competition.
General purpose scope to us for everything on a bolt gun: This was a close call between Premier LT and March 3-24x42. Ultimately, Premier's 50mm objective is a little better for low light and 15x is plenty for general purpose use. Other good quality scopes of similar magnification range are almost invariable much heavier which I dislike. Leupold Mark 6 3-18x44 is another option, but I have not tested it yet.
General purpose scopes to use for everything on a semi-auto: just about all my semi-auto rifles are AR-15 variants and the largest of them sports an 18" barrel. I generally prefer smallish scopes on ARs and like to have comparatively low magnifications available. March's 1-8x24 is compact, fairly light and excellent optically and mechanically. The reticle needs work, but it is usable. 8x top end is plenty for the distances I am willing to explore with my ARs. If March or someone else made a 1.5-12x32FFP scope I would go with that one, but 1-8x24 is good enough. Leupold Mark 8 1-8x24 is a nice scope as well, but I am not convinced I like the squeeze turrets until I test them carefully. IOR 1-10x26 is too heavy for this application, although a nice design.
Big game hunting scope: I first toyed with calling this category "conventional bolt guns", but that was too vague. I have seen just about every hunting scope out there and the Leica ER is as good as anything for a bit less money. The view is spectacular. The eyepiece is very forgiving. Tracking with the exposed turret is dead on. Reticle selection is reasonable. 3.5-14x is sufficient range of magnification to tackle everything other than charging rhinos.
Low range variable that can do both CQB and mid-range: I could have selected the March 1-8x24 for this or something similar, but in this category performance at 1x becomes more important. Moreover, I want that 1x performance to be good with and without reticle illumination. SWFA SS 1-6x24 is excellent at 1x even without a illumination, while dialing up to 6x takes me pretty far out.
Red dot: Micro Aimpoint is rugged and the battery last forever. It is also small enough to serve as a supplementary sight if need be,
ILya
