I've migrated everything from Google except for Google Voice. I have yet to find an alternative that can match the feature set and ease of use, regardless of the cost.
I've been using voip.ms for over a decade, they have a great feature set and are very affordable.
What part of the feature set in particular has been lacking in competitors?
EDIT: asking because I've been working on an alternative of sorts. I used GV a lot before I figured I could go without it/Google.