Alternator AC DELCO or GENERAL MOTORS

On that list, I'd only go with the AC Delco.

Only brand here I am confident with is ACDELCO, Wai I’ve installed due to customer already having the part but I cannot swear to its reliability.

AC Delco makes a good product. Alternator technology is really old, so it's not difficult to do right.

I have the acdelco in my old Comanche and it works great.

Personally the AcDelco would be my top choice here with these options going new and not a reman.

If those are your only options you're gonna go with, Remy or ACDELCO. Keep in mind the ACDELCO is not made by ACDELCO and is just rebranded. But has a warranty and decent support.

Honestly, even the AC Delco quality is questionable.

The issue you can run into is most common vehicle alternators are light duty at best. Lets say its a 100 amp alt, don't pull more than 40 amps continuous. A great example is the AC Delco 10si alternator. Loads of cheap knock offs and copies of that alternator all claiming crazy high amperage but none list the duty cycle. The 10si frame is designed for 40 amps of power and the heat that creates. You might be able to get a little more cooling with a better fan but you won't get 100+ amps out of one.

Had an appetite for alternators, as they put it behind the rear cylinder head and tried to keep it cool with some little rubber/plastic air duct. Failboat. We sold the car with its third alternator, each failure attributed to failure of the rear bearings.

Oh yeah and it went through 2 maybe 3 alternators in the 13 years we had it lol.