Between the two, can summarize as follows ...
1) If you want super hand holding, particularly with family, and mobile app, and don't mind mega privacy issues, go with Casa.
2) If you already understand multisig, and want collaboration for Business/Retirement account type purposes, go with Unchained.
I generally recommend Unchained
Both offer collaborative multisig, though Casa has varying levels with different annual costs. Both offer access to buy Bitcoin and stack directly into your account. The keychecks with Unchained are easier when your keys are remote compared to Casa.
Here's some notes I made from a few years ago, and some of the concerns have since been addressed