It depends on your current gear, tbh, and whether or not you'll be killing A6S this week. If you ARE killing it and you get the tomestone (or you already have one) the weapon is the obvious choice. If you're not, you should be looking at a few *really good* pieces:

Legs
Boots
Ring

More or less in that order. Because the Midan Jacket is so sexy, you'll end up wanting the SKS from the Midan Mask to supplement the dearth of it you'll get from upgrading crafted (70 sks) to Midan (0 sks). The legs will always be bis - you'll likely not even consider using the 240 Midan (78 acc / 112 sks...) over the 230 Slips, especially since you'll likely be first or second in line for a Twine, anyway, and those pants should be the first upgrade.

The boots are kinda debatable, since if you don't need the acc, the Midas ones are way better, but you can meld 18 Crit into them compared to what 12 det? 18 acc? so it's not really as far off as it seems at first, imo.

Ring is always a safe bet, ears and wrist are pretty safe bets, but you'll be using Midas over them if it drops (until they're 240). The hands are also a pretty okay purchase, but you might wanna be rocking the Midas ones while you have the crafted chest, if you care about keeping approximately 600 skill speed.

Things to think about.

The slipstream hat is a really good choice, too, it's just very likely to be replaced by the Midas helm eventually when you down A8S, whereas the slipstream boots, pants, and ring are unlikely to ever leave your character once they're on.