Are they all still locked to an MDM profile, if so while they're yours, at any point you could lose access to them and that sucks. There's a ton of laptops that have been up on Ebay that ended up having mdm. We bought a few on accident for our non-profit. Fortunately we were able to find the original owners and they were gracious to remove them. We were also lucky they hadn't been disabled. Thing is most people don't realize that when you restore / setup that laptop it will pull that profile regardless of how you wipe or clear it.
TLDR; Make sure MDM profiles are gone and the laptops are cleared before doing anything personal :D