We are still using FellowshipOne for registration but are moving over to Stripe for payment processing. They take 2.9% + $0.30 on every transaction (which is almost half what we use now) and have an awesome API and JavaScript plugin for your website.
SecureGive for us, it has worked well without any problems and the fees are reasonable. We use it on our website/mobile app for giving, we don’t do much on paid event registrations so we haven’t needed that.