It depends heavily on what move set you are using... specifically if it has which of the following: DD / Sub / Roost (or Rest???), and if you're holding leftovers or Lum (or something else)? An all out-attacker or something that you want to have just one DD (or Hone Claws I guess) you might just want to stick with the offensive 252 speed and attack spread, whereas if you're aiming to get multiple DDs or HCs, then maybe something more defensive. If it's DD, then you can take some (or all) of it from Speed into HP (i.e. it could run 252 HP 252 Attack). If it's HC... then I dunno. You probably should have a list of things you aim to outspeed and then have speed based on that and put the rest in HP.