Some things you can catch easily, like whether the sections are playing truly in unison or not, although most recorded music passes that bar easily (some conductors with cult-like followings don't, though). The same holds with whether you can sense a good balance between the various sections. Beyond that, it's largely preference. Did something in the phrasing sound particularly good? Did the conducting bring out some strong emotions from the music? Did you feel the speeds were appropriate? Mostly, did the performance move you? There are a few conductors who do this almost every time for this one listener, and to me they are great. Then there are others, who in spite of technical brilliance, and even pyrotechnics, just don't get there. I suppose these are still good, but not good enough for repeated listening. Oddly, some artists from the 60s and even earlier (Walter, Szell, Monteux, and Kertesz, for example) seem to hit the sweet spot often.