AF +1

depending on what you have access to and how much you like to play nin prety much decides what you should upgrade.

if you have access to acp body and plan to use it for nin, acc+dw beats just about any body piece (even if it's marginally). there's almost no situation where you'll have capped acc on nin and even when you're close enough to use AF you'll still want to be using food like pizza. acp body gains almost 3% in total dot over af+1 because of the acc alone, slightly more because of the fSTR bonus it gets from 5 str (even when solo SH is very hard to beat, less time casting shadows leaves more time to auto-attack). the 3% dw comes out to slightly more than 3% dot and also increases tp gain at the delay too, slightly edging out HQ haub's 1% acc and ~2.6% damage boost from atk (which is even less considering you'll want to use pizza as much as possible).

enkidu v. af+1 is a bit more edgy. af+1 definately gives higher damage, but the acc from enkidu is very hard to overlook. even with a completely optimized WS kit I'm only at 400 acc before food, which only caps acc on about half of event mobs outside of big NMs.

having taken the acp+enkidu route myself, I really wish I had upgraded feet first and only. gotta admit that af+1 body does look hot for walking around in though, lol.