Summoner Necros are the greatest.
No I ain't trollin, I just love having so may pets. Also pre-patch they are even better, 50 skeletons yay!
Pre-patch skeletons were horrendous. Once you got to about halfway through Nightmare they were being one-shot by everything. Now Summon Necros are definitely the easiest class to run through with. Smiter Paladins are the most powerful once they've reached lvl 98 with full equipment, however.