I cannot say what "most" are looking for. But in general people either want a flat frequency response or an EBS (extended bass shelf) for their frequency response.
Home theater guys will dismiss group delay. Some music guys say it matters and it is why they build huge sealed boxes
.
Most on these boards care about f3 frequency (where the low end rolls off to 3 dB down). Most also care about SPL.
If you continue to investigate you will probably find that you cannot produce significant SPL < 30Hz with a 10" driver. Also 20 Litre is about the volume of the bracing + driver + port for most of the subs people build in these forums
. You really need a larger volume to produce significant SPL at low frequencies. A 100 Litre box is considered medium to small.
That being said some sub is better then none. Keep playing with WinISD. It should set the tuning for you when you specify the alignment you want.
Have fun!