Depends somewhat on your fundage. Me, I'd get a Leece-Neville 24V alt. Costs around 200 bucks or so. Mind you, I'm a well established Hundredaire... ;-)
I have a LN-555 alt that I used to charge my 12V bank for years. I ran the crap outta that thing, pulling max amps for hours at a time. Still nothing wrong with the alt, it outlasted the Honda motor powering it.
I'm going to 48V, so I'm looking for a way to do that.