Well, in the 3 or 4 campaigns I've played in so far, the most powerful damage outputter was always the archer.
Consider this, two fighters one melee and one archer.
Their 2 prime stats are 14 and 20 at first level. The melee having 20 str and 16 dex (lets assume dex for this arguement), and the other way around for the archer.
By 20th level, they can have a +6 enhancement bonus to each of their stats (I'm going for the most extreme version, it is only slightly lesser for lower levels). Plus, they'll put all 4 stat increases into their prime stat
This means that the melee fighter is using a two handed weapon (as most melee fighters do in my experience), great sword with a +5 enhancement bonus and +10 strength bonus. Because it's two handed, plus WS for a total of +22 damage. Assuming WF, he gets 5 attacks at +36/+31/+26/+21/+16
The archer is using a +4 mighty bow with +5 enhancement bonus and +5 arrows. He has point blank shot, rapid shot, WF, WS, bracers of archery. That means his total damage bonus with one arrow when within 30ft is +18. (if your DM allows +5 mighty bows like mine did, then this would be +19) However, his pluses to hit and attacks are: +44/+39/+34/+29/+24. That means the archer can take his option to fire another arrow each round for -2 to hit and STILL get better bonuses to hit than the meleer. Even if his enemies are getting +4 ac due to cover bonuses, the archer STILL gets more pluses to hit, with more attacks.
Defensively the archer is ALSO better as with the proper armor or magic items, you can easily rival full plate +5 due to the much higher dex.
If you're wondering about being within 30ft, almost every battle in every campaign I've played in started at about 50 ft away. Often less. It wasn't too dangerous getting close, no one could hit our archer. When it was hit turn he took a 5ft step back and fired(until he became an order of the bow initiate, then he was getting sneak attack damage fairly often and being able to fire while in melee as well). Keep in mind that the archer can spread his attacks out amongst almost every monster on the battlefield as well, if he kills a monster with each arrow, he doesn't have to worry about which ones are within melee range.
As for grappling, keep in mind that you have to make a melee touch attack to start grappling. A normal fighter is easy to hit, not normally more than ac 16 for touch(ring of prot +5, only +1 from dex due to full plate). While the archer has a touch ac of 25 assuming a +5 ring of protection.
Using the old feats a two weapon fighter wouldn't fare too much better, they need two feats to match the archers extra attack, and they have to spend extra money to buy a second weapon just as magical as the first. They only get half their strength bonus on their extra attack, however, instead of the full +4 for the archer.
Purely just changing it so arrows don't stack any more would solve most of the problem. Plus, the change to TWF/weapon finesse will balance out two weapon fighters.
Majoru Oakheart
Yes I do too much math, I can't help it