which iv set for Julia?

I would think that her speed is pretty important. Probably better to go with -Res.

Then again, Julia's main job now-a-days is a dragon killer... She could also become a ploy user, but that would mean a -spd bane...

But neutral speed is pretty bad itself in many cases...

+res -spd, her speed is already really lackluster, and her res is quite important since she can be a pretty good magic tanker *cough Reinhardt cough*, and she can use ploys really well, especially with a boon.

The chain of command from most to least important for Julia is atk>spd=res>def>hp. A res bane Julia can’t run ploys really well, but she can still tank Reinhardt. A speed bane Julia has no hope of doubling anyone not named Reinhardt, and will most likely be doubled by anyone anyway. A neutral speed keeps it to where dragons won’t totally obliterate her, and I personally have a +atk-res Julia who does her job (dragon slaying and Reinhardt blocking) fantastically. I’d say go for +hp-res and slap a green tomebreaker on her to screw Nino and Cecilia, it’s what I do and it works.

+Res/-Spd. While Spd would preferably be neutral, it's bad enough already that you don't lose out on too much by taking a hit. Whereas her Res, which is easily one of her best features, can boost her ability to tank mages and ploy with a boon - and, vice versa, is impacted a lot more by taking a bane. The only problem with Spd, as TG pointed out, is that it allows dragons to potentially double, but you should be one-shotting Nowi on initiating anyway (and not letting her into you) so it's all good.