What kind of apparel filters would be useful? Blunt/Piercing/Heat & Cold/Warmth?
This probably won't work with Outfitter. You can try though. Worst case you'll just have to deconstruct all change dressers then disable this mod. This mod allows for pawn-specific outfits to be created - works will with infused apparel - so Outfitter is not really needed.
Well, I would split them into two or more types: soldier, worker, etc.
Dependent on the type, other features of apparel become important.
Generally, it would be nice to sort and filter by: name, layer(s) used by the clothes, quality, current durability, weapon range, weapon damage (+ [number of shots]) , heat insulation, cold insulation, movement speed buff/debuff, mental break threshold, social impact. I think these are always important to see and should cover a great percentage of needs.
Secondly, I would like a separate filter for infused or enchanted items (from Infused or A Rimworld of Magic) and maybe other similar mods, if possible.
For soldiers, we definitely need the armor type protections: heat, blunt, sharp, harmony (this is from a mod I think - A Rimworld of Magic), etc. Then the offensive stats like accuracy, rate of fire, cooldowns, armor penetration, stopping power (this is modded in my game), aiming time, etc.
For workers, the other types of stats become important, like: mining speed, global work speed, global learning factor, research speed, plant work speed, tame animal chance, negotiation ability, toxic sensitivity, etc. I'm not sure which are vanilla and which are from Infused, but I never play without that mod

Some stats could come from "A Rimworld of magic" too but might not be shown on the apparel piece (i.e. after enchanting something with gems).
Lastly, it very much depends on how easy it is to see all of this information for each pawn, i.e. showing how the pawn's stats change when you add/remove a piece of apparel would be really cool, as well as their current job priorities (or at least those that have the highest priority - it's gonna get complicated when not using manual priorities though).
Also, the most important thing for me is to be able to do multiple sorting and/or filtering (i.e. for more than one stat at the same time).
PS: I know I'm asking for a lot and maybe for impossible stuff, but this is just what perfection would look like for me

It's not my intention to offend nor undermine your work!
Thanks!