Both specs can get utterly boring after a while. Doing quests like the Nesingwary grinds as a Muti rogue can be highly annoying, while at the same time it also sucks if you could stealth past mobs and have to do that at regular reduced speed.
I'd look at your server environment mostly. I'm on a PvP server with a totally messed up faction ratio. This results in spending just about as much time on world PvP as I do on the actual quests. Combat is less than ideal for that.
Planning on doing instances as you level? Blade Flurry, Adrenaline Rush, and Killing Spree will put you significantly above other rogues since there is no FoK to compensate until level 80. (not like you could keep up with mages or hunters)
Then there is weapons...
Sure, BoA daggers would make up for the dagger shortage until you hit Outland, but once you hit the mid-70s you'll have a ton of daggers from quests and instances to pick from. Titansteel Shanker and Paper Cutter are guaranteed "drops" at 80. It doesn't look so great for Combat then. You're getting truly amazing Fists from both a quest and Nexus and Utgarde Keep once you get to Northrend, but things are a mess between 75 and 80. Seems like you're dealing with shortage and oversupply either way, just at different times in your leveling career.
Planning on doing a Pally or Warrior at some point? A BoA sword would be awsome to have then, while no class can really make efficient use of daggers other than rogues.
What about money on your main toon(s)? I bought my rogue dual-spec at 70, so now I can switch between a hack'n'slash combat build for grinding quests and the occasional dungeon and an ambushing Sub build for world PvP and times when I want to be sneaky. Best 1000g I spent on an alt so far since playing (and leveling) an alt has to be all about fun for me. Dual-spec gives me just that, because I can perfectly match my playing style to my mood as well as complete quests in the most efficient way.
Btw, the best way to spend tokens (if you havent done so yet) is to buy the WG shoulders. The 10% XP bonus is huge and will benefit whatever spec you decide to level with. Plus them being leather means that anything you could roll in the future will benefit as well, unless you decide to roll a clothie.
So... I think a BoA sword is overall the best choice. If combat starts to bore you sh*tless, you could always do a Hemo build or some crazy hybrid or whatever for some variety. It's just questing after all. Hell, you wouldn't even have to change glyphs if you get the Evis one, which should be mandatory for leveling anyway regardless of what spec you choose.
Little edit to elaborate on the choices at 75-80:
If you wanted Combat, unless you were a blacksmith or have a BoA sword, you'd be Combat Maces to make use of
Crimson Cranium Crusher (Amphitheater of Anguish)
There just isn't any alternative. No fist at all, and the only decent MH sword available at 75 (74 actually) would be
Savage Cobalt Slicer (crafted)
You could get lucky at 78 in UP and get
Ymiron's Blade
Unfortunately this sword isn't even an upgrade to the CCC. Same goes for
Corroded Saronite Edge
This one you couldn't even get unless you were a blacksmith.
At the same time though, you have four MH daggers to choose from:
http://www.wowhead.com/?compare=44746;41183;44051;41825
They're all so damn close in their stats that it doesn't even matter which one you pick for your final stretch of leveling.
So ultimately, this here is what you need to work with:
http://www.wowhead.com/?compare=41824;41182;37065;41186;37065;44096;42944;44746;41825;41183;44051
At 80 your BoA weapons will be obsolete since there will be the full array of BoE weapons available to you as well as those from the Argent Tournament. So frankly, unless you have another future alt in mind, you might be better off just buying honor tokens and whatnot if you have too many badges laying around. You can easily do
Combat Swords now until you hit Northrend
Combat Fists Northrend Start until 75
Combat Maces or Mutilate 75-80
without having any significant disadvantage compared to using the BoA weapons.
Bah, another addition:
Forgot to put the Emblem heirloom sword into the comparison, but not gonna change that again. Also, the heirloom weapons are well worth the old unrestricted enchants, so that's something to consider as well. If nothing else, it wins on the coolness factor. (2x15 agi just ain't that great anymore once you're 70+)
Edited, Aug 1st 2009 10:41am by Kanngarnix