What's great
I've been managing all my WordPress sites with Modular DS for about 10 months. It's reliable, easy to use, and has great features from the basics of updating themes, plugins and core, to backups, security and reporting. Recently they have added a Psychiatric integration and an automated visual check, to ensure sites have not broken after updates - very handy!
The team is constantly adding great new features and the odd time I have had an issue, support has been responsive and helpful.
The pricing is also sensible to scale unlike some of its competitors.
I thoroughly recommend ModularDS.
What needs improvement
I'm still waiting for automated cache clearing after updates to support the plugin I use, but the fact they have already implemented this for the most popular cache plugins is testament to their commitment to adding features that we need.
vs Alternatives
ManageWP
MalCare
WP UmbrellaGreat features, easy to use with a sustainable, scalable pricing structure