What is the best app for creating and signing documents on the iPad?

I am a home organizer and I am typically in a clients home when I need to have them sign a contract and I want to become a 'paperless' organizer. I need to take my service agreement, enter their information, have them sign the document and then email it to both them and myself. I don't want my 'template' altered in the process and I don't need to worry about saving the document since it will be in my inbox. Can anyone suggest the best app to accomplish this? Thank you in advance for all your help.