Drive connection type: SATA vs. SAS nowadays, maybe FC?
Capacity
Rot. speed 5500/7200/10000/15000 RPM
seek time (is more or less dependent on rot. speed)
Cost/GB
Not sure what you mean by accessories, though, so some guesses:
Hot swap case for drives
RAID controller
RAID box (i.e. 16disk SATA->FC etc).
Priorities are totally dependent on what you need the server to do and what your budget is.
I.e. if you just need a box to dump files on, without the need for zero downtime and high speeds, you could use server class SATA drives and a software RAID, but if you have a medium-sized database where you need extremely fast query times, you might use a fast SSD drive. So please tell us what you want to do so you can get more helpful infos.
The metrics:
Not sure what you mean by accessories, though, so some guesses:
Priorities are totally dependent on what you need the server to do and what your budget is.
I.e. if you just need a box to dump files on, without the need for zero downtime and high speeds, you could use server class SATA drives and a software RAID, but if you have a medium-sized database where you need extremely fast query times, you might use a fast SSD drive. So please tell us what you want to do so you can get more helpful infos.
There are many comparison factors such as:
1- Speed / RPM.
2- HD drive is hot-swappable or not.
3- Capacity.
4- Form factor.
5- Interface.
6- Power consumption.
7- Cost.
The priority depends mainly on your needs / requirements.