Of units mentioned in the first post I use but three
On regular basis, that is. Plus EGD, but you haven't specifically mentioned them.
Inquisitors - for my mage their rage-building ability is quite important, so I use them for 50-66% of game. They can be cloned with phantom, and I found that I more often used their Rage ability three times, instead of using Rage twice and Resurrection once. But after certain level they are not needed. If there were seven base slots...
Paladins - they are quintessential and it's easiest to fight some bosses with them. I don't like fighting bosses at all. I take them when I can. Oh, and they abide by the laws of coexistence when it comes to undead, I like it. I feel forced to use them sometimes though, that's why they may fit the hate-love relationship role.
Rune Mage - They Are Awesome. Archmage Skill For The Win. Zap Mooks To Death. And Clone, He He He.
I like to use Black Knights occasionally, but they are costly to heal. Their redeeming feature is their cool appearance.
Engineers I liked first, and used, but I prefer Alchemists, because they possess similar sturdiness but better effect-to-leadership ratio.