Honestly depends on their recovery time.
11 has the quickest start-up at 7 frames (always look at the entry for the first hit for start-up times) with 7 frames. It is however a high/high string, so if your opponent is able to block the first hit they can duck the second and punish. The range is poor though so the first hit might wiff if you've been pushed back.
f222 and 223 have the same start-up (13 frames). f222 will do more damage and leave you neutral on block. 223 does less damage, has a gap between two and 3 (only punishable by moves with instant armour), but leaves you +6 on block allowing you to set up some frame traps. Most specials will miss if cancelled into from 223, but doing the non-cancelled version will make it hit (also means you don't need to worry about hit-confirming it).
Of course, the quickest move is D1 (6f start-up) for when you absolutely, positively need to poke quickly, and the move can be cancelled into specials. Will give the lowest damage of all. Range is also pretty bad.
