More definition is required. I will guess shallower than 328'/100 Meters, above freezing, and a 300 Bar DIN connection is a reasonable criterion.
I personally have not seen a mediocre performing regulator (excluding combo octo/BC fillers) in decades not saying there are aren't any, I just have not had the misfortune in a long time. I suggest the following procedure:
Cut 1: The two best sources I can think of to answer your question are dive shop rental fleets and large regulator repair companies. Dive shops can't afford gear that doesn't withstand far more abuse than good sense allows. Some shops may try to intimidate ill-informed customers into buying the most expensive regulator, but that is not the one that they invest in or are numerically more likely to be sued over. Large regulator repair shops see a lot of products over long periods with rare failures. I my experience, bad regulators are far more likely to be unreliable or difficult to repair than exhibit poor breathing characteristics.
Cut 2: Scratch models that are not available with a 300 Bar DIN option. Most regulators today are so they can sell in other markets.
Cut 3: It is unlikely to have made it past Cut 1, but eliminate regulators that are very new to the market or are not produced in the large numbers. The idea is to let the real world prove all the different aspects that make a good purchase rather than some dork with a financial incentive or a desire to justify a poorly researched purchase.
Cut 4: Examine what's left to see if personal ergonomic preferences emerge. Taking note of specific feature complaints expressed by friends and on forums like this can help you determine what might be important or annoying to you. Indulge country of origin biases at this point if you are inclined.
Cut 5: Rent one or more remaining candidates to make sure things like hose lengths work, bubbles don't annoy you, or the first stage doesn't interfere with gear you already own and like.
Cut 6: All things being equal, there is nothing wrong with choosing the lowest cost regulator from the list. The reason is not to be cheap (as in my case), but your preferences may evolve and you shouldn't be reluctant to upgrade because you spent too darn much.
Let us know how you vote with your money and why.