Ask HN: What's the best email capture form to use?

Quick question to the HN crowd: What's the best email capture form to use?

I'm just putting up a splash screen that shows what's to come of the company and the visitor can input their email to receive a beta invite down the road.

I'd like for it to just be an email submit form that uses an email auto-responder (one I can customize) and manages the list of people that sign up. Possibility of managing future email contact with users would be a plus.

Does not need to be a free service. I've searched for the service and haven't came across any customizable ones yet that I can use with my own design. Any recommendations?