as far as i'm concerned, it really depends on the band.
i'm not particularly keen on listening to, say, a new paul mccartney live album, simply because his approach to live playing is to largely try to reproduce the studio material as best as possible. under conditions like that, most of the songs suffer. his studio craftsmanship is near immaculate, and though i'm sure his concerts are fun and everything, subtleities of the kind he usually pulls off while recording (which make his albums so listenable) are lost. ergo, i prefer the studio stuff.
for bands like the who, zeppelin and mick taylor era stones, it's quite different because their concerts are disrelated to their studio work.
in 1969, the who recorded two albums, 'tommy' and 'live at leeds', and it's hard to tell they're the same band.
simply because on stage, they're edgy and loud; improvising the hell out of every song, which is enjoyable in a completely different way from their studio stuff.
so, yes, back to my original point (such as it is): some bands are 'live' bands, who have the stuff it takes to truly play for the moment. some bands aren't.
on a more personal level, i usually enjoy listening to live albums, whatever their artistic merits, because i like such 'exciting' stuff as hearing audiences react to songs etc., but that's just me!
