It's good to see this thread still alive. We spent a lot of time on M7 a while back, and frankly preferences are all over the place. Personally, I prefer recordings that acknowledge the madcap, Marx Brothers finale for what it is: zany fun. That requires a fairly fast tempo, and that really narrows the field. Kondrashin/Concertgebouw is a scintillating live reading. The Michael T Thomas with the London SYmphony on RCA is extremely fine -- so the brilliant version heard in SF last year shouldn't be a surprise. I like Bernstein/Sony, but not the DG -- too slow.
I enjoyed Abbado/Chicago, but was underwhelmed with the Berlin remake. I can't figure out what all the fuss was about.
Chailly, Maazel, Levi all have fine readings of the first four movements, but let me down in the finale.
A highly rated performance by M Gielen is well worth its price.
If great sound isn't necessary, several of Hermann Scherchen's mono recordings are really good -- even if the orchestral playing is never above mediocre.
The Inbal is generally ok, except for some missing trombones in the first movement due to a bad edit. Kubelik with NY in their Mahler set is much better than his DG. Boulez is great if you like that approach (who can match the Cleveland orchestra?). Levine on RCA is excellent and the sound is sensational.
Ones I can't stand: Solti (no humor, too serious), Masur (he doesn't get it), Rattle (I don't understand how he is so highly regarded as a Mahler conductor) and Bruno Maderna (execrable playing). The Hans Rosbaud is interesting, but the playing and recording are crude. Abravanel's orchestra just can't muster the sound needed, and he is lackluster.
Sorry to be so long-winded, but the 7th is also my favorite Mahler symphony.
In a nutshell: go for Thomas, since the Kondrashin is generally not available. This ranking will likely change when the Thomas/SF/SACD comes out.