Once you get past the size aperature and type reticle, then a lot of other factors pop up.
Will a riser at extra cost be needed? What type battery power, is the effective battery life acceptable? Weight? Type of mount, do you really need to take it off and have it return to zero? Warranty and service? What reports do you have from other owners, what's the company background?
In your list of choices I ordered them in my research Lucid, Sparc, PA. I view good customer service as having the better design so it won't need postage at all. It boils down to the vendor cranking out better quality, which is going to cost more, so you do get what you pay for.
Red dots are a bit pricey overall, compared to the same money in binoculars you get half as many lenses that don't focus and are simple flats. Add an LED and voila, all thats left is making it so it won't fall apart. IIRC all three of these sights are made in the same plant in China, along with Eotech and Aimpoint components, which goes to show each has their own quality standards to research.
One way to help select would be to write down the features you have, prioritized, and then rate the scopes as you see it, 1 - 2 - 3. Lowest score wins, buy it and try it.
If it's has any impact at all, I believe the one reason Aimpoint came out with the PRO was to compete directly against the Lucid. It's that good and they couldn't ignore the money going to them.
