The verdict
For a small B2B team running Google Ads, perhaps with some Meta, I would start with Adzooma. The free plan lets you connect a real account and see what an audit finds before you spend anything.
If paid search is a major cost line and one person looks at several Google and Microsoft accounts every week, pick Adalysis. The audits are the product, and they pay off when somebody acts on them.
If you run one small account, I would not buy either until the free route has told you something useful. Whichever you choose, give one person the job of reading the alerts.