I would go with Weaponsmith, since most of the high level armor can only be worn by a rather selective group of classes. On top of that, the item sets that drop in Instances are far better than most that can be made, most people wouldn't pay the amount you would want either, especially if you buy or farm for your own mats. I find that being a weaponsmith will lead to better riches, however both aren't easy at all. Finding or buying high level plans for making items is a real pain. Being able to use the plans is another issue since you still require level 300. Then gathering the materials will take forever unless you buy them, which will cost you a boatload of money. Currently I'm at BS 276, and I chose weaponsmithing, I'll probably go with master axe for my guild buds. I'm a patient guy so I'm not complaining on how long it takes to level Blacksmithing, the payoff for me is being able to make great weapons, including the heartseeker.
A great weapon that sells very well is the Phantom Blade, it's super popular with combat/stun lock spec-ed rogues. It's not that difficult to make compared to higher level items either.
I'm a rogue so it's kinda odd that I'm a blacksmith, however it does make life easy when it comes to mining. I make plenty of cash off of selling mithril bars. I hardly need them anymore, but other blacksmiths and engineers buy em up super fast! If you know an enchanter you can make plenty of cash selling enchanted thorium bars as well.
Corvino(Akama)[Alliance]