What are the trade-offs between an Account Engagement form and a form handler?

Account Engagement forms give you progressive profiling, dependent fields, built-in spam protection, and styling through layout templates — the platform renders the form, so it can make decisions at render time. The trade-off is that the form is Account Engagement's, so it does not carry any custom validation or back-end integration the web team already built.

Form handlers accept a POST from an existing third-party form. That preserves whatever the development team built — custom validation, a CRM write, a payment step — and still creates the prospect and fires completion actions. What you lose is progressive profiling and dependent fields, and you inherit the maintenance burden: if the developers rename a field on the front end and nobody updates the mapping, data silently stops flowing.

My default is Account Engagement forms for marketing content, and form handlers only where an existing form genuinely cannot be replaced. Where I do use form handlers, I insist on documenting the field mapping and monitoring submissions for a drop-off.