The verdict
If you work only in Google and Microsoft Ads and your problem is finding what has gone wrong, I would pick Adalysis. It is the simpler product to adopt, and the audits tell you where to look.
If you run more platforms, or want rules that flag or fix problems on their own, pick Optmyzr. Start with alerts and move to automated changes once you trust a rule, because a bad rule can do the wrong thing at scale.
If you manage one small account, I would skip both. Either way, the value depends on a person acting on what the tool finds.