Comment It depends on your needs but (Score 2, Informative) 183
I have had success with both OpenSRS and GoDaddy for SSL certs.
OpenSRS will allow you to easily supply the needs of your customers.
Never had a problem with using either.
Also, what type of support do you need? My experience is you install them and they work, then you renew them/reinstall as needed.
just mu $0.02