first thing to keep in mind is EQ2 and EQ1 are completely different games.
With that said, I would stick to a pet class, or a warrior class to keep things simple.
Pet class:
Conjuror
Necromancer
Warrior Class:
Bezerker
Guardian
Every class has its ups and downs. All classes are fun, it just depends on what you like to do. Shadow Knights and Paladins can be a bit more difficult. They combine spells with combat abilities of a warrior class. Paladins relie on their healing abilities to survive a fight and normally have lower Damage. The Shadow Knight has higher damage abilities, normally from their ability to life tap and such.
In the end, youll get the most benefit from try evcery class out. play them to level 10, and then pick the one you like best.