50’s-early 60’s were the worst.
And I’d say the 00’s were the best, though in two distinct phases with a brief nadir between them.
The decade began with the twilight of O’Neill-directed Bat Office that had exploded the Batfamily and nailed several successful crossover in the 90’s - and that decade is a strong #2 in terms of quality in my opinion. But because the 00’s started out from that high point, you had a few years of residual greatness from that era for its beginning - Batgirl with Cassandra Cain, Bruce Wayne: Murderer, the end of Dixon’s runs on Nightwing and Robin, etc. Then the wheels fell off for a bit when O’Neill retired and other from the era also left, and we got botched stuff like Wargames or sprinkled with stuff like Hush, Gotham Central, and Brubaker’s Catwoman underneath. There were some growing pains when OYL happened, but eventually we settled into the RIP/INC era, which wasn’t as cohesive as O’Neill’s era, but saw a super star stable explode everything.