If you are managing the host, then it is better to stick with the current version as you may face some compatibility issues with it. I have read a couple of feedback from users where they migrated to the new version and then found issues with it, which is not an issue though, but just compatibility thing. I have a couple of my websites on wpengine, and I have recently upgraded to the php 7.1 and haven't encountered any issues till yet. The whole idea is that if you have a good managed wordpress hosting plan, then compatibility also won't be an issue for your website as they do the technical changes and check for you.