Warning wall of text. Just pick a paragraph
What I've noticed over the years is that classes move in "seasons"
From my experience in cRPG (at the time of my joining this mod, Oct-ish 2010), it was shielder central. If you didn't have a shield, you got shot. This was the phasing out of the archer era.
From what I've seen it's been
archers > shielders > horses > polearms > 2h > archers/ranged > crossbowery (the age of the Chaos Operators) > horse archers + crossbows > shielders +2h > horses > polearms (and then the nerf) > horses + shielders (current)
This is pulling off the trend off the top of my head (based on failing memory and natural predators). Of course the 2h heroes have really persisted throughout the trends, simply that their tactics change and hybrids are used (instead of pure 2h).
At the time of the Chaos crossbros, I noticed the increase in horse archers to naturally prey on the immobility of the Operators (when they needed the reload). From there, we saw some foot archers spring up to counter that, which lead to more lancer cav to prey on the archers etc.
As cRPG grows and matures (in development, nothing to say about the community), the combat becomes a more even spread, as fighters realize after a bit that joint operations by several different classes functions better, instead of one merry-go-round of counter-classing (yes it's cool to see a legion with identical armor and weapons, but there is no variation in combat potential, which means easy defeat from ONE predator).
The only major exception which ran counter to my trend model (that crude arrow thing up three paragraphs) is the [horses > polearm > horses] section. I assume it's because the polearms got the nerf (which we had coming), but nothing came to the cavalry, which is - as of now - severely overpowered. They got an indirect buff simply because their melee counter-class has been compromised (because people haven't yet adapted; give it time), range remains a viable counter to horses, but are vulnerable to the speeding, backstabbing cherry picker poopooheads (I'm one) that represent the cav class (both scout and mounted infantry).
Right now, shielders are a fad. Much like the FotM weapons that you find throughout the months of gameplay. Remember when the Bec de Corbin with the fucking biggest dildo on the sex market? Now check the marketplace and see how many are flooding it.
Shielding will have its time, axes and polearms will come into play to counteract the shielding crew. Then the 2h heroes will have their age again. This is just the way of cRPG.