So, I’ll preface my response with this, I’ve been a Medium Armor mage for over 900 hours of gameplay on my US East character (My main) because i’ve been more or less forced into playing on 360ms latency in fights (Because all my friends live near that server so i wouldnt force them to play EU with me). Medium armor gave me that safety net of “Oh i have an extra dodge, more armor and i only do 10% less damage than light players ?” So that was an obvious choice for both survival and DPS while under those conditions.
I recently made an EUCentral character to level up and play PvP with <150ms (in most times, except for when the server randomly lags for 10 seconds at a time), This character has been running Light armor Mage (same as my other USE character build wise except armor class). Having hit level 60 yesterday and immediately gone up to 550GS by spending the 70k i saved up on some good light gear for PvP and 600GS weapons, So far from what i can see, If you have 2 brain cells to rub together for warmth, You can do so much more with light armor right now vs medium. Allow me to explain my opinion on that further.
Medium armor, around 1350/1350 resistances, Plus any gems you equip (I run full Onyx’s for that bonus 20% mitigation vs all physical damage (Damn musket spammers are the bane of my existance). I was STILL taking upward of 2500 damage from a powder burn shot, Plus the extra 2k it would do in ticks over 13 seconds. Spear players would STILL crit me for over 1800 damage plus bleed stacks/CC/Rend/Slow or whatever other CC they had on said abilities. Great Axe Gravity well would STILL suck me into the center even if my heel was BARELY inside the AoE of it, Resulting in me having to waste 2 of my 3 dodges just to get out of it’s slow radius while my head got caved in by the other team.
Light armor currently as of my understanding (haven’t caught up on the patch notes in a month, So some of these might have been changed/reverted), Light armor now gets 3 dodges with hearty rings, going double the distance of Medium dodges, Light armor deals 20% Bonus damage just for existing vs Mediums 10% bonus, Light armor also gets I believe 30% bonus healing from Life stave users just for existing vs Mediums neutral 0% bonus and heavies -30% heal strength (for SOME reason, Like anti heal doesnt exist in the game for a reason).
Light armor more or less has made me go from “Oh no I might actually die to this 3 man who’s attempting to gank me” to more along the lines of “Oh no, They’re about to waste their time chasing me when i can just Dodge to double my distance, Dodge again for even more distance, Drop Slows/AoE’s to hinder them while i get MORE distance since my stamina has half regened in the time it took to cast those, Let me dodge again” Or better yet, All of that PLUS a Rapier with Evade for +20 stam every use and Fleche for an extra 10m distance between me and them. Either they chase me and never catch me if i play correctly, Or i run medium and more or less have half the escape-ability with less healing, 10% less damage output as a DPS and what feels like the same resistances in group fights anyway.
The extra resistances in PvP and PvE In my opinion, In 90% of situations don’t matter worth a damn and that is the ONLY thing that Medium armor had going for it since light and heavy got 3 dodges with Hearty rings. You can simply run x3+ Resilience stacks on your armor or Shirking Fortification (OR BOTH in my EUC characters case) and most players only manage to kill you IF they get on top of you with hard CC and you forget where your dodge button is. 
I feel there should be an even representation of ALL types of armors/weapons, Not "Oh here’s 40 players in this OPR Match, 25 of them will be Light armor Dexterity players running Rapier/Spear/Musket/Bow with the same 3 or 4 abilities on every setup, 3 Tanks struggling to do their jobs and survive since they don’t heal anywhere near as much, 6 Mages running the same damn loadouts with Ice/Fire/Void if they want CC’s or anti-heal vs light armors 30% bonus and the 6 healers all running Light armor with a Life Stave and Rapier so they get 3 dodges, Plus self heals, Plus Fleche and another Dodge after they use Evade (with I-Frames) for the +20 stamina instantly.
Long wall of text, for that I apologize, But the sad state of the armor spread among players right now is something I feel fairly strongly about.