I'd recommend human for a first try at either of those classes, honestly. Either would be enough of a challenge without a high XP penalty.

Human for both also allows you a balanced approach to your class abilities, which I think is a good starting point for figuring them out. A d-elf conjurer, for example, will always struggle with elementals (relative to the human conjurer) even if they do everything right, and your first time out it may be hard to spot the difference between "This is working badly because of what I am" vs. "I'm making some serious mistake."

Both (assuming evil conjurer) are high-offense low-defense characters; by the time a fight that you don't want is initiated, it may be too late to save your life.

Of the two, I think an A-P is probably a bit new player friendlier; at least you probably won't lose con to your own class abilities.

With either of these classes (and some people disagree with me on this point), if you have an interest in PK, I think it's easier to try at let's say level 15 and try to figure out how to make it work, then level a bit and do so again with a few new abilities and repeat vs. power to hero and try to figure out how to PK with dozens of abilities that you've never used and probably don't understand very well. A level 15 A-P already has a lot of different options in combat and it takes some experience to figure out when bash is a good idea vs. trip vs. disarming vs. direct damage spells vs. maledictions etc.