I'm gonna assume we're talking airsoft repros here and not rs, so any advice is to be taken with a "depends which nameless chinese factory yours rolled out of".
I'd avoid the switchable elcan spectres, primary issue being zero retention between modes. They're also bulky, heavy and only offer a single position. Shame as they are a cool looking optic.
Acogs, well it depends on the repro most likely.
Short dots/lpvo's are better, but again a mixed bag and the ones i've used you never get the same kind of 1x that you'd get from a red dot. Others can comment as i've heard folks talking up some specific brands being much much better than others in this regard.
What i found that worked really quite well was a short dot+stacked red dot. Bore offset is a minor annoyance for having a quick, intuitive switch between the true open fov of a red dot and the "is this guy taking the mick or am i missing?" Power of a magnified optic. Only thing is i found that i'd be using the red dot about 99.9% of the time such that when i did use the magnified i'd find i had forgotten to re-zero it since the last [event requiring a re-zero].
A fixed magnification would provably work as well if you're stacking, i had a 1-6 and it basically lived its life at 4 and i probably wouldnt have missed the adjustment.
