What matters depends on what kind of climbing you plan to do.
Length matters if you’re climbing (and/or rappelling) routes longer than 25 meters. In some areas, a 80m rope is essential, in others a 50m will do just fine.
Impact force matters if you climb on marginal protection. (Ice, hard trad, aid)
Diameter matters if you put the rope to heavy use, since a fatter rope takes more wear. Also the diameter must be compatible with your brake. Thinner is easier to feet through a belay device, but might take more practice to belay safely with.
number of UIAA falls matters if you work hard on redpointing. I.e if you fall a lot.
Weight matters if you want to push your grades.
Dry treatment matters on multi-pitch climbing and is vital on ice. Not so important for sport crafting though.
What also matters a lot is how the rope handles. (Though that is not clear from technical specs). Some ropes become twisted and tangled easier than others.
(Edit after additional information in question)
For indoors use, get a short (50m will be enough at almost any gym) durable (ie not too thin, 10-10.2 mm perhaps) rope. Don’t bother with dry treatment, obviously.
Indoor training tends to be more intense than outdoor cragging, so a high number of uiaa falls is good, albeit not a deal breaker.