Ok so i started a Dunmer Assassin with the back story that he was once part of the Morag Tong long ago. So my question is should i join the Dark Brotherhood or destroy them? A certain Dumer Thief in the TG will tell you about how the Tong and DB kill each other on 1st site but the DB are the only Assassin quest-friendly group so that is alot of Sneaky loot im missing out on. Also what would look the most fitting for a Tong Uniform?

Destroy them. The Dark Brotherhood essentially split from the Morag Tong and are basically a bastardization of the Morag Tong's values. And the Morag Tong do not have a "uniform" to speak of- simple leathers will do as most members seem to wear it.

Remember, the Morag Tong are honroable. Something the Dark Brotherhood isn't.

So then how will i go about being a "good" assassin in skyrim? Even the TG are not Robin Hood like in OB

By assassinating bandits and other evil-doers. The Morang Tong were legally sanctioned assassins.

they in now way were good at all, just legal and honorable in the sights of the great houses in their ability to take out targets. they were neither good not bad, their indiscrimate killers just like the DB, they were just legal and able to operate within the realms of the law. I see the main difference in them besides who they worship and how they get thier contracts, is their mentatlity. but ya so far they are enemys per se, but as unknown morag tong its up to you. i mean the whole reason why they became legal wasbecause of a deal with vehk in that they had to worship the tribunaral which was one the main reasons that caused the split. You could join seeing how the db were right in splitting seeing how the tribuneral wee false gods that were put down and that u carry on that still has backing from a being that most would claim is higher or same level but seperate than an aedra. You dont have to become a raving lunatic, just bask in the kill alone and not in the money like the morag tong was.

theres pelnty there now with events that have passed since morrowind to justify to ur charector for joining. hell at the end u can see it as evolving the guild with ur charector.

Legal only within the realm of Morrowind. Outside of that boundary and they were fair game for local law and enforcers.

Of course, the Dark Brotherhood have a stronger presence outside of Morrowind, too. In fact, the only Morag Tong assassin outside of Morrowind was the one who the Champion of Cyrodill may have met while trying to find Mehrune's Razor. The Morag Tong are strictly assassins for the political system of Morrowind, and aren't likely to take on targets outside of that country anyway. It's unlikely that a Great House would try to get the Morag Tong to kill someone in, say, Hammerfell unless the target was a Member of one of the Great Houses trying to escape punishment.

Join the Brotherhood, use them to sign your pact with Mephala.

Well the Tong is disbanded but i feel this Char will still follow their ways