What are good trade skills for Rogues?Follow

I am looking for some advice on trade skills. My favorite character is a Rogue and I am looking for a good trade skills to make him complete. I have read that:

1) Engineering is the best trade skill to get if you are into PvP.. exspecially if you go Gnomish.

2)Alchemy seems to be a common choice... exspecially the Alchemy/Herbalism choice.

3)Enchanting seems to be the hardest trade skill.

4)Leatherworking is a common choice for Rogues, but is it really that good?

These are the main 4 I am looking at right now. I am not into PvP right now... though I will say that I will eventually try it(I have had bad experiance's in MUD's with PvP) So that kinda leaves Engineering out. Herbalism seems kind of boring... I am not sure I want to do it. I am seriously considering Leatherworking, but can't you buy your leather armor in AH? I am leaning towards Alchemy because I like the idea of using potions to buff yourself and heal yourself. I am also leaning towards Enchanting because it appeals to me.. enchant yourself and enchant your armor and weapons.. A question I have about this is can you ADD your own enchantment to ALREADY enchanted items? Any advice would be appreciated.