Arkhan is nasty on the battlefield. He has some sick magic, a handful of good buffs for your soldiers and some really great dialogue. His early vampire units are really good to have because the Crypt Ghouls and wolves are excellent flankers the Tomb Kings don't have in the early game. His unique items are pretty powerful, too. He has the least exciting mount options (steed and chariot only) but he's still a total beast on both. Khatep's casket of souls mount is so ridiculous that I can't wait to see it in action.
Gonna try Khalida next and then ME campaigns with Khatep and Settra. I might give Steel Faith Overhaul 2 a run. Anyone try this mod out? The gist of it is the mod makes high tier units, like Blood Knights, lesser in numbers but much deadlier and harder to take down in a battle. Lords become killing machines, even more than the base game lol, and battles last roughly 30% longer because everything gets a health buff. Also, buildings are reworked for 4 slot settlements and lore-friendly units were added to the mod.
I'm not on Discord but I'll make an account soon. I'm on Asia time so not too sure if our schedules will mesh. I'd also be up for a head to head or co-op campaign sometime if you or anyone else is interested. Can be as slow as we want or whatever.