"Best" is subjective to each person.
I have Tijicons, Meprolights, XS, AmeriGlo, TruGlo TFO, on my GLOCKs.
My favorite is the AmeriGlo Pro Operator.
It all depends on what you are looking for.
Installation is not hard with the proper tools, many have installed the rear sights with a hammer and a punch, screw driver, dowel rod, ect.
But do you really want to "beat" an expensive night sight into the dovetail?
Up until last year the stock front GLOCK sight was pinned, and could easily be remove with a set of pliers. Now they are held like the aftermarket sights with a small hex head screw. Some companies furnish this nut driver with their night sight sets.
I have Trijicon, Meprolight, and Novaks. I like the Trijicons the best.
Currently looking for someone local with a sight tool to remove my sights so I can refinish my slide. Also need night sights installed on my HK when I get them. I don't want to do the hammer and punch method because I don't want to risk breaking the tritium vial, or marring the sight.
I'm casting my vote for Meprolights. I've got two Glocks with a green dot up front and orange dots in the rear. I think the Meps are not as bright but I really like the two colors.
I also have a G23 with factory Glock night sights and I like them too except for the fact that they're all green. They're way brighter than the Meps though.