Omapure seems pretty expensive to me. Natural Factors
and Jarrows Formulas
are half the cost (both WFS). I wouldn't worry about IFOS, but that is just me. I don't have any issues with the Costco brand, good choice too.
As for ratios, most seem to be in the 2:1 range. I would like to find a 1:1 EPA/DHA in a high amount per capsule at a decent price, but not going to lose any sleep over it.