The hands down best PvE class in the game is the Summoner. Highest DPS in the game while being massively tanky. Zero artifact Summoner has better DPS than a lot of classes get with significant artifact investment, and it's the hands down tankiest class in the game. It's also a rock solid PvP class with a very low skill floor; being a great Summoner is difficult, but being an acceptable Summoner is maybe 15 minutes of work and it consists of one attack alias and a trigger for shield detection.
Predator gets some fancy tricks for PvE, but the damage output without artifacts is sort of lackluster and their tankiness is pretty low. Leather armor, banded, shield, spacing, vitality effect. No sip bonus, no con boost, no passive healing, etc. The fancy tricks can be nice if you want to try something like soloing a caravan or something, but for your everyday bashing the Summoner beats it hands down. This is especially true if you don't have artifacts, especially because you can get a reliable welfare diadem that's an effective +15% DPS for Summoners. Predator is also clownshoes-tier as far as PvP goes.
Druid is tanky with high DPS that varies due to generating and spending resources. Very fun class and a PvP powerhouse.
Berserker is decently tanky while having good DPS. The big thing about a Berserker is that they're the cheapest class to artifact up for bashing because they use shield attacks for PvE and artifact shields are much cheaper than artifact weapons and collars. It's also a very easy class for group PvP with a lot of power and a ton of utility.
All three knight classes(Deathknight/Templar/Runeguard) are solid contenders. Decent DPS, solid tank, tons of utility. Good at bashing, good-to-great in PvP.
So, I'd go with Summoner or Deathknight for demonic, Berserker or Templar for Anti-magick, and Druid or Runeguard for Magick.
"On the battlefield I am a god. I love war. The steel, the smell, the corpses. I wish there were more. On the first day I drove the Northmen back alone at the ford. Alone! On the second I carried the bridge! Me! Yesterday I climbed the Heroes! I love war! I… I wish it wasn’t over."