As evidenced in this post by Mecha Mario, Omega Override, when base stats are tied, takes the one closest to the top.
I think it should go off of base stats, then stat bonuses, then top-bottom.
Ranloth -> RE: Omega Override (4/7/2013 19:49:07)
Nope. This would be even worse with Malf and Smoke because it'd target totally different stat than intended. Then it'd have to be coded to ignore every single nerfer (existing + future ones) to not affect the way it works it. It's fine as it is, you should have both types anyway (if Dex/Tech combo) so it won't be a disadvantage. Likewise with Strength/Support - lower damage taken in. Simple as.
King Helios -> RE: Omega Override (4/7/2013 19:51:58)
Huh? I'm not talking about it going off of them.
Example:
STR: 45 DEX: 50 +25 TEC: 50 +29 SUP: 45
It would take the 30% from the 50 tech, as opposed to the 50 DEX, because the 50 tech is off of a higher stat bonus.
If it were:
STR: 45 +20 DEX: 46 TEC: 45 +20 SUP: 45 +10
It would go off of dex, because that has the highest base stat.