I used the "industrial" rustoleum 2 part, 3 times now in different garages. This last time, I put in the behr silica grip powder on the 2nd coat (I bought 2 of the 89$ industrial epoxies, since it's a 2.5+ car garage).
Make sure you get a couple rollers, I recommend a strong roller stick, and the widest roller, and the wide home depot bucket. Mix for 30 minutes in this sort of weather, and roll within 2 hours of mixing (otherwise it gets really gummy as it cures in the bucket).
You MUST prep the floor well for it to stick well, a 5 parts water, 1 part muriatic acid solution will clean it pretty good, I did that AND pressure washed the concrete since in my new house, it looked nasty to begin with. Try and do it during the day, since there are so many bugs at night that just get stuck everywhere.
Don't walk on it for at LEAST 48 hours, if not more. It won't chip or crack in 24 hours, but it will pick up dirt permanently. Heavy traffic is ok after about 3-4 days, don't turn tires w/o rolling the car, it can screw it up.
Oh, and the acid wash, can create a nasty odor/chemical that burns your eyes/throat, so wear a mask and some glasses at least. Don't get it on your clothes or skin. Roll in straight lines in 1/4 sections of the garage, and work your way out the door, don't trap yourself somewhere haha

. Overlap the edges so you don't see streaks, and roll multiple times over the same area. Before I forget, use a small paint brush (2"?) to outline the garage floor so you don't try and roll it ALL with your roller. You will need 2 or more rollers as they tend to gum up (or even break) pretty well, and also 2 or more applicators.