The verdict
For a small B2B team sending contracts and NDAs, I'd pick Dropbox Sign. The signing step becomes boring, which is what you want, and the free plan lets you test it with real documents. I'd pick Acrobat Sign when the team already pays for Acrobat, lives in Microsoft 365 or Salesforce, or has security reviews that ask for the certifications Adobe lists.
If you need workflows, proposal building or heavy volume, you may outgrow Dropbox Sign. In that case, look at Docusign or PandaDoc rather than forcing either of these. Also remember that Dropbox Sign sells its API separately from the web app.