I think the English version of the old saying is "you get what you pay for".
My experience with rebuilt parts is VERY SPOTTY unless it is a large firm that specializes in rebuilds. Any "fly by night" rebuild(like many discount parts stores sell) is highly suspect and my experience is that you will get to replace that part again, lifetime guarantee or not. I did this three times once on a rebuilt alternator in less than a month, that was a Datsun truck. Datsun tells you how long ago that was.
If at all possible and at a reasonable price I always use OEM or well known name brand aftermarket parts. My experience is much better with those.
However, an alternator is not hard to rebuild yourself as long as you didn't let it get so bad that there are metal filings inside etc. All you need is some new bearings, and motor cleaner plus some time. Never had a regulator or diode blow except once when I jump started with wrong polarity, duh. So can't say how long those will last other than I never replaced one that just wore out.
Rebuilt many alternators in my past with reliability as good as the original. Haven't done it lately since alternators seem to last much longer than back before about the 90s, so new alternators may be trickier, but I doubt it would be terribly so.
Just my experience,
Jim Henderson