The only other 'white-glove' provider I've used was Voxrox (Which became Voxel, and then got bought out by Internap iirc) - They had amazing support up until they got bought out by Internap. It really boils down to getting extremely competent support on the first try every time and having 911's answered within seconds. It's a pretty amazing thing to be woken up at 2AM by your own monitoring, put in a 911 ticket, and literally get a actionable response in seconds.

The place I am at now has servers at Rackspace and we can't even get ticketing and other alerts to go through systems like PagerDuty from your own internal systems.