Personally I think TGS is by far the best book in the second part of the series. It has its problems, but they are much less severe than those of book 7-11, in which Jordan lost control of the plot, let side stories get expanded to a ridiculous degree, and build most of the plot on the characters behaving stupidly and out of character at plot convenient moments instead of keeping them consistent. It's not the lack of action and battles that's the problem for me, I've never cared much about this stuff anyway.

The Shadow Rising and The Fires of Heaven are the best books in the series IMO, and Jordan at his best was better and polished writer than Sanderson for sure, but I honestly find it hard to understand those people who claim that Sanderson's books are clearly the worst and they drag the series down. TGS is much closer in quality to TFOH and TSR than CoT is to TGS, and ye, Cot is inferior to TGS, thanks for asking. ToM is much inferior to TGS IMO, but still easily better than books 8-10. The series was already dragged down by Jordan producing successive subpar books before Sanderson took over.