If you are looking for an electronic signature provider, the most important thing to look for is whether or not the company you are planning to use is in full compliance with all of the appropriate laws, rules and regulations. In the United States for example we have to very well defined laws that explain what it takes to make an electronic signature legal.
The Laws Covering the Use of an Electronic Signature
Here in the US these laws are the ENSIGN Act and UETA and any provider you decide to contact regarding your electronic signature should be able to provide you with proof that are in full compliance with both of these laws. All of the software we use in the provision of electronic signatures is in compliance and the e signatures that it creates are completely viable should you ever need to use them in a court of law.