At first level, it's unsurprising that a polarm fighter with dodge, mobility, and spring attack kicks but....he's breaking the rules. Spring Attack requires a +4 BAB.
As to the rest, I like Improved Initiative and Two weapon fighting.
Initiative bonusses do become a matter of diminishing returns at mid to high levels but, as many people have pointed out, a lot of foes have more than a +0 init modifier. There are plenty of creatures with high initiative modifiers out there (including other rogues and wizards/etc who took Improved Initiative--and note that Imp Init is one of the feats that commonly shows up on NPCs since most throwaway combat NPCs will never see any use out of skill focus: craft (armorsmith) or Craft Ring but will be helped by Imp Init). If your base comparison is a +4 init modifier (an NPC fighter with no dex and Imp Init), Imp Init looks a lot better.
Dodge, Mobility, and Spring Attack is a good route to go down as well. A lot of times, you'll have to tumble into a flank to get sneak attacks so you're only going to get one attack anyway. Spring Attack lets you get in for that sneak attack and then retreat to safety. (Incidentally, that's an argument for Martial Weap Prof: Greatsword as well--often you won't be able to make full attacks from a flanking position).
Two Weapon Fighting is another viable route. I'd recommend starting with a quarterstaff and then trading it in for a shortsword/rapier or handaxe/rapier as soon as you can afford a masterwork buckler. (The -1 to hit won't hurt when you can't make a full attack and won't hurt too much when you can. And the +1 AC (and later more) will help when you can't make full attacks). If you take a class that gives shield proficiency, you should consider Improved Buckler Defense from CW to keep the buckler bonus while attacking. (Alternately, you could switch to a light shield and take Imp Shield Bash from the PH and avoid the -1 penalty to hit at the cost of dropping your base damage from d6 to d4).