Just starting my main quest only playthrough and wanted to know which pre defined class would be best for a dark elf?

It depends entirely on what type of character you want. Do you want to focus on Magic, Combat, or Stealth?
Dunmer can fit into any archetype quite well.

Most people create a custom class, because a lot of the pre-made classes use some skills that are odd choices.

well since i was combat in skyrim gonna stick with combat again in morrowind

As Pluto said, Dunmer tend to be one of the most flexible and least archetypal of all TES races; they can adapt to whatever class you give them quite well. I always use custom classes, but if you really want a pre-built one my instinct would say spellsword, witchhunter, or sorcerer. But since you said you wanted a more combat-oriented character, perhaps a Scout.

You can see the Dunmer racial skill bonuses http://www.uesp.net/wiki/Morrowind:Dunmer to help match up when picking your class.
And the http://morrowind.inventivegamer.com/tools/chargen/ is great for planning before you go in-game.

You might want to try Assassin, Scout, Rouge, or Spellsword..... But I still suggest just making a custom class instead.