The verdict
If you have not written your ads yet, start with the Transparency site. It takes minutes, and it can change how you write a first ad. It shows what was shown, not what worked, so treat it as inspiration.
If you already spend on Google Ads or Microsoft Ads and want fewer manual checks, Adalysis does the daily checking for you. The Transparency site cannot do that, because it measures nothing in your account.
Plenty of teams will use both at different stages: research before the campaign, audits once it is live. Do not pay for Adalysis to do competitor research. It is not built for it.