I chose Gravity Payments, mostly because of their support, but also because they are local to me.
I have 4 direct contacts with their cell phone numbers and also within an hour's drive of me.
I know that sounds crazy, and it isn't like I'm actually going to show up at their house or anything. That's not the important bit; what is important is that they get my business and the context I'm working in, and they get the context of all my clients, and they personally onboard each of my clients with me, and are the same contact month after month. If that sounds like old school and friction, you're right, it is. But it makes for a much smoother experience when anything abnormal (but legitimate, or authorized) happens down the road. For example, when a client has an unusually high transaction on Stripe, their mostly useless fraud detection blocks it, and also likely puts the whole account on hold. If you can even get a hold of support within a few days, after a few more days of automated responses, you have a different support agent on the end of each response. Now, not only do you get someone every few days, you also have to rehash the whole issue over and over again. After that, you have to go through endless hoops to prove who you are, your business legality, etc. Stripe is the arbiter of truth, and they hold your money until you've danced to their jig.
Contrast that with Gravity, where I'm usually one phone call away from direct support who is in my zip code and already knows all about me and my clients and their context, and if he's on vacation or busy, I have three backups. Plus their general support line, but I've never even needed that.
It's a refreshing concept from the "good ole days" when you actually personally knew the person responsible for making sure your payments work, and can fix it when they don't. It shouldn't have to be a concept though, or even rare. But it is, unfortunately.
Also, I don't work for gravity and never have, I've just been overly pleased with their gateway for 6+ years, as I've watched the Stripe train go from "can't do any wrong" to "whoa....watch out! Let that train pass..."