I'd say stick with crit for the crazy fun procs. That, or switch to Stamina. Explanation follows.

The haste will not materially affect your MW procs. 1% haste would mean that for every 100 MW proccing hits, you'll have an extra one. Look at it this way: it takes five procs to get the instant cast. If you want to get your fifth proc at the time you currently get to four, then you'll need 25% more procs in that time (because you want one extra in the time you get four). Gemming alone won't get that much haste, and fights in pvp are pretty darn fast. Additionally, haste will not affect your windfury procs either, due to WF's internal cooldown.

If you're talking about just having more fun, consider stamina gems. I went with all stamina gems on a mage in the past, and found that my total amount of wreckage went up and I got to use a more fun and in-your-face playstyle. Because of the amount of stamina on gems, it actually adds up to an appreciable difference, where the other offensive stats are more marginal.

As for AP, I'd avoid it. You're better off with Agility or Intellect, even at half the AP values, because of the other benefits (spell crit/mana pool, melee crit/armor/dodge).