I suggest neither because I have a Dell t20
and for future proofing they suck. Only one fan in rear for ventilation. Now if you only plan to ever run one or two disk and that nvme than you may be ok. Just remember going forward you will hit a limit with the case and motherboard layout.
a lot relies on the motherboard. many dells designed the motherboard so that it could only be used in a specific case.
many could be mounted in different cases (IE. larger cases and with the use of additional fans (those types you could connect to the power supply) cooling and space was not an issue.
with this in consideration will the board be sufficient and will it offer opportunities for future upgrade.
dell does make some good systems But as @ sanfordvdev stated they suck for future proofing. (Not to mention sometimes the bios may be problematic.
For most system i build I avoid dells
just about any atx case will do
I usually build custom stand alone servers so i tend to pick up cases with a lot of room for drives and preferably multiple places for cooling gear
( gaming cases are really good for this)
but for server purposes they dont have to be pretty just big enough for the number of drives you wish to put in them.
quite often with some systems brought into my shop If the case and power supply is in good shape it gets a good cleaning and is put aside for building someone a cheap nas server
not generally usually you have to purchase a server with a backplane set up for psu redundancy such as some dell poweredge server systems, and ibm server systems (High end machines) and those are not cheap.