I had been using One-Handed Melee Weapons throughout the entire game, occasionally using Ranged Weapons or Magic.

I decided to switch it up a bit to see how Two-Handed Melee Weapons work and I am shocked at how bad they are.

-Drain much more stamina from use compared to One-Handed Melee Weapons.
-Much, MUCH slower attacks.
-Applies the same amount of elemental effect per strike as a One-Handed Melee Weapon, despite being much slower and more draining. Plus, I fewer Two-Handed Melee Weapons seem to even have elemental effects.
-Can Parry attacks but cannot Counterattack, which means no bonus damage, no knockdown and no power attacks on downed foes.
-Cannot be used with the Jet Pack skill Floating, making them almost entirely useless against flying enemies and less good for potent attacks from air.

Plus, all those are already on top of the facts that you cannot wield a Shield and they don't particularly deal higher damage except for the most powerful variants which require a LOT of Strength. The very high-Strength ones that deal tons of damage at least have that advantage, but the slower attacks, greater stamina drain and lack of counterattacks likely outweigh even this advantage.

What do you guys think? If you've used both One-Handed and Two-Handed Melee Weapons a fair bit, what have been your experiences?

I have not used 2h in Elex II but did in Elex 1, and I remember them being fairly bad in that game, too.