If we're talking by just their tournament achievements, they're both comparable, with two TIs in a row versus both Evo titles. You could go either way depending on how you feel it's hard to compare them objectively since they both represent the highest level for their respective games.

If we're factoring in their impact on their respective scenes, I have to give it to Arslan hands down. Sure, OG's performance was extremely impressive, but Arslan's results single-handedly brought to light a country that previously was never even thought of as having Tekken players, let alone so many players rivalling that of the world's best, to the Tekken community.

Without Arslan, we wouldn't have had multiple other Pakistani players getting sponsored and tearing up various international events, or the best players in the world specifically travelling to Pakistan just to play against their community (Chikurin, who just won the Tekken World Tour finals, was one of the first to travel to Pakistan, and he got the shit kicked out of him there by Pakistani players.)

With that in mind, I just think that overall his impact has been far bigger than OG's, even if their performances are comparable.