They all seem to have pluses and minuses.
Vortex Defenders and Monsterum are hit and miss. If you get the size that fits right, the rubber isn't horrible, and one that has a good "snap" when closing they are great. However that's only about 50% of the time if you are lucky. I've found the Monsterum often fit looser esp. in the eyepiece even when you get the recommended size. The vortex are okay if you get a set that has a good click when they shut. They both seem to run into 1 of 2 issues if they have them.
- The rubber is bad, I recently got a set of Vortex defenders where the rubber had basically no stretch at all, I've had others split over time.
- The caps don't stay securely closed. Some are super tight, others flip open if you look at them wrong. Monsterum seems to have less issue with this than Vortex.
Butler creek.....if you get a set that fits well, they aren't horrible. They do break though and don't fold flat, super cheap for a range only gun though. If you happen to have a scope their flex version fits on well they are pretty good. Like the vortex/monsterum they become unreliable if they fit too loose or too tight.
Aadland....expensive but nice. Honestly the objective at times is almost too hard to close. I wish they installed deeper onto the scope body so that it was attached to something besides just the adjustable eyepiece focus. I just got a set for a razor g3 and it only contacts the adjustable eyepiece so it often moves/rotates. I guess on the flip side you can make small eyepiece focus adjustments without removing the cap
100 Concepts looked cool, until I saw that it's $155+ shipping/tax for a set and they are basically ARD only. I'm just not that high speed.
DT Works looked interesting, but again mostly only ARD options, and it's unclear how the retaining colar stays in place, if it's just friction fit etc.
As for the air bulb they do make smaller sizes, and they are never a bad idea to have in a range bag to just blow off a lens. Though frankly after doing photography for 30+ years, most file owners would be SHOCKED how much of an obstruction you can have in a lens and not visibly see it.