I need to migrate a client from Dropbox to Google Drive and am looking for a utility to do a cloud to cloud sync. I've looked at a dozen or so apps that do what I'm looking for, but choosing one seems like a crapshoot. They all seem to have some type of limitation, either low data caps, bandwidth throttling, lack of technical support. I'm hoping someone can recommend an app or service you've actually used or have confidence in. It doesn't have to be free.
This is to move approximately 700 GB of data and would be a one-time sync. Dependability, speed, trustworthiness, and support are the key things I'm looking for. Any suggestions are appreciated.