My vote is for equal availability, and I'd like to break my reasoning down into two sections.

First we have lore consistency-- if a certain weapon type, say, poison, was common in the wastes, then the powers that be would have developed countermeasures. Plus if there's a power field that can stop fire, it would be used in power armor as well as deflector fields.

Secondly there is the game effects. If there is one armor type that a class doesn't have, then the desirability of that ammo type becomes proportionate to the population of that class. It also would affect the economy, as weapons become less desirable if they cannot deal the favored damage type. In addition, if a class has a serious strength then you have a meta-advantage in deciding what to whack them with. For example, if spies have superior poison resist you know to stow your poison weapon and pull your fire one.
In addition, any class weakness or strengths would unbalance PvE farming, in proportion to their desireability for common/valuable NPC types. Force and Pierce are fairly universal, the "off types" are usually considered X-ray, Poison and Fire. You see this effect with Drones and their weakness to fire, "Droners don't go to Cycrow" is a saying for a reason, and not just because it rhymes nicely. Superior X-ray resist would make a class far superior to any other for farming WoC disks, and an inferiority in fire armor would make a class drag on in levelling as they have to avoid El Farid, and far inferior for farming rare parts without hacking, as they can't do fire mobs.

In addition, there's so many bosses and dungeon areas in the game that don't have any, or many, notable drops. No one bothers with Soul Caves anymore, and I'm not sure anything of note drops there (if there was would anyone know? I'd wager the number of boss kills in all of titan's history is less than ten). We could even use dungeons in Neocron to fill in the the mid-TLs too, a Mutant King with some TL40 armor drops. Maybe a mid-level dungeon designed for grouping that teaches the concepts used in endgame stuff. A sort of MC-5 light... an MC-2.5 if you will.