Cloud Email Forensics Tools - Gmail, Yahoo, etc

I have used Transend email migration tool in the past. Works great and is able to pull a mailbox and convert it into a PST.

I too have had some success with X1 Social Discovery. My best experience is using Aid4Mail, hands down the best one I've used and does conversions too. Microsoft Outlook works as well, but be careful and make sure you get all the attachments. I've had some success with Nuix and some failures as well. Cellebrite Cloud Analyzer is for Law Enforcement only.

Aid4Mail is the one you want!