If that title seems like "faint praise", it is not meant to. I think there are probably other performances less well recorded which I sometimes prefer, but most of these are of a high standard - a bit like the old (and sometimes underrated) Leinsdorf cycle from the 1970s.
I may even give some detailed comment on each symphony when I've listened a few times, but in the meantime, here are my initial assessments of each work, recording quality in all is very good:
No 1 Three stars.
No 2 Four stars. (Beware Gergiev's LSO disc - fabulous string playing in the second movement ruined by his tuneless, thoughtless groaning!)
No 3 Five stars.
No 4 Five stars.
No 5 Three stars.
No 6 Five stars.
No 7 Four stars.