@Kaldo
Syno DS224+. Good bang vs. buck. Decent speed, decent features (iGPU, Docker, VMs).
My only gripe(s): only 2 USB ports, no built-in 2.5 GbE (possible via USB and 3rd party driver) and Synology's limited list of "approved" HDDs.
Yes. If your HDD is formatted as NTFS or exFAT, no reformat should be necessary.
What do you mean by docker drives?
Mainly the drives.
My DS216+II runs 24/7 for 7 years now without hiccup (but, obvisously, YMMV). DSM supports drive migration.