It all depends on what you mean by quality.
Are you talking about potency where you get the most epa/dha per capsule, or are you talking about purity, where the most pollutants have been removed.
If, according to Biotest's recent articles, DHA is more important the EPA for a male weightlifter, then Biotest's new Flameout is the most potent fish oil on the market.(Note: I cannot speak about Biotest's quality control or purity standards for this product, but if it is anything like their other products, then I suspect it to be very good).
The only other product that I have found that comes remotely close is Nordic Naturals Pro DHA. It is not as potent as Biotest's Flameout (you get 375 mg DHA/100mh Epa per capsule) but the purity of the fish oil is very high.
Hope this helps.