Red dot sights?

You'll want to avoid the cheaper ones, they come from china and pretty much you get what you pay for. Just about everyone makes red dot scopes now, I would examine the reputable manufacturers and chose the one you like. Of course, lifetime warranties are nice.

MEL

how much do you want to spend?
for $400 you can get the one i have, the Aimpoint ML2
its what navy seals use and i think its a great scope... maybe on the expensive side but i dont think you will find a better one for the money
my personal favorite is the Leupold Mk4 CQ/T which i dont have yet!!!
its big, its expensive ($900 i think) and they are of the same quality that all Leupolds are of
all these are good tactical red dot sights which cost a LOT i hope someone else can tell you about others that might be more practical for your needs