You have a few choices really.

a) Take what is most useful for PvP or PvE.
b) Take what is most useful for gold generation.
c) Don't bother much with tradeskills.

For PvE, I'd look at inscription, as the shoulders a bit further ahead of the Hodir shoulders, the other professions are ahead of their counterparts (example Enchanting rings vs unenchanted rings); plus that way you don't have to worry about Hodir faction at all.

For PvP, Engineering seems to be a very strong choice across the toons.

For Gold, you can concentrate on cooldowns, or you can attempt to have one of each profession and then use arbitrage to play the market. Look at the cost of the mats, and what you can do with the mats, and if there is a difference in your favor. There will be a lot that are good, and most won't be, but you can offer to buy stacks in trade, and make what is profitable; you'll make a lot more per hour buying mats then you will farming. In general gathering skills are good for low-income/starting, but production skills make more down the road.

Alternatively, do a mix of these.