Well, if we're going to discuss the flavor of more than whitetails and mule deer, then antelope will usually win--unless, of course, they haven't been taken care of properly in the field. Pronghorn meat deteriorates quicker than whitetail or mule deer meat when not cooled down pretty quickly. It's kind of like the difference between salmon and walleye. Walleye can take some"field abuse," but salmon not so much.
I am also convinced that pronghorn meat contains some chemical that tastes nasty to a FEW people--just as some people get a soapy flavor from cilantro. Have known a few people who cannot stand pronghorn meat, even when everybody else eating the same meal thinks it's great.
Whether any sort of game meat is better than another also depends on cooking method. The longer any kind of red meat is cooked, the tougher it gets, and the more "flavor" it develops. Whether the flavor is pleasing to any individual depends on their taste-buds. I know plenty of people who cannot stand to eat even medium-rare meat, preferring well-done. Some game stands up better to what many would call "over-cooking" than others, often due to a higher fat content. Fat in domestic meat (and some game) has a sweet taste, which is why many people used to domestic beef and pork don't like game--and also why many game recipes include some extra fat (such as butter or bacon) and/or sweet ingredients, such as jellies or fruit. (This also applies to darker-meated game birds.)
Then there's the "what we're used to" syndrome. Many hunters who go to Africa claim eland is the BEST meat, but I suspect this is because eland tastes more like beef than most African big game, because of its fat content, which allows it to be cooked anywhere from rare to well-done and still taste good--or at least "familiar." Other African game is typically leaner, so can't be cooked at such a wide range of temperatures and still taste "good." But I've eaten plenty of African game that's at least as good as eland, if lightly cooked, including springbok, zebra and even the weird-looking black wildebeest. In fact one of the top chefs in Johannesburg years ago often chose a backstrap of black wildebeest for a customer-impressing meal.
So yeah, it all depends on personal taste, field care and the cook.
