27" late 2012 iMac Hard Drive Compatibility?
What 3TB hard drives are compatible with my late 2012 27" MD096LL/A imac?
型号：A1419／ 2012／2.9 & 3.2 GHz Core i5 or 3.4 GHz Core i7 专业版
Surprising you can use just about anyone's that physically fits. The issue most people encounter is the HD internal thermal sensor and how Apple accesses it. Some HD's now support the newer SMART standard that works in Apple systems. With these HD's you just swap over the drive. Even still you can still use a non-comforming HD by using OWC adapter: iMac HD upgrade kit. It also has the adhesive strips you'll need.
As to what drive to get I would recommend going with a SSHD which is a hybrid drive. Seagate makes a good one so does Western Digital.