There's one way I judge: price. YGWYPF... almost every time.
Cheaper ones are more likely to have noisy fans that run all the time. Even the cheapest auto parts store ones will work, for a while, but if you want something you don't have to replace in 3 years, spend the money. More expensive products aren't a conspiracy. And since you're looking at big wattage, it's likely the real cheap ones won't live up to those ratings.
Other than that, weight will tell you about quality. The internals are NOT the same.
