I've thrown in my answers to these questions previously but the more I go to Africa, the more varied the opinions become. So instead of being general, let me be pretty specific.
Impala from the Zimbabwe/Botswana border of both sexes, quantity 9, were excellent as steaks and also as mince jaffals. I sincerely believe Impala is better than Kudu but Kudu gets more credit because its a more "noble" beast.
Cape Buffalo Dugga Boy from the Zambezi Valley - Had oxtail and other dishes that tasted just as they would in America using the same ingredients. I think Cape Buffalo tastes like spent dairy cow. Not super tender. Tastes like beef. Its just fine. The marrow is where the good stuff is!
Giraffe, an old stink bull taken from the Zimbabwe/Botswana border. Inedible as it was too tough even after tenderizing to be anything but chewy. We're talking about chewing for 60 seconds per bite! The "stink" of the giraffe was in the meat just like a sheep has a stink that gives lamb and mutton its taste. While an odd taste, Giraffe has the makings of good eating if you were hunting young females or culls I suspect. Just stay away from stink bulls.
Waterbuck, known by one and all in Africa to be putrid, disgusting, musky, and to be avoided. The Waterbuck trophy bulls, quantity two, that I ate in the Zambezi Valley for many, many meals were some of the finest game I've ever tasted. One such occasion certainly made my "top-20" meals of all time. I'm a total food snob, take the compliment as high as it is intended.
Hippo. Several friends say its the best meals they've ever, ever had. Hippo steak is supposed to be fantastic with one friend having ate I believe 6-8 of them in one sitting. My hippo was tough but not an unpleasant meal.
Bushbuck. We ate bushbuck marrow in brown gravy over buttered, toasted garlic bread. This was another top-20 memorable meals of my life. The steaks and all other portions were also 8 out of 10.
Kudu. It's fine. It's way over hyped. I eat it gladly but I would not wax poetical about the very young bull I harvested at the Zim/Bots border that should have been perfection, nor was the trophy bull from the Zambezi Valley something I would blather on about extensively. Its a solid 7 out of 10 meat, its just not made with the tears of angels.
Zebra. I love this stuff! Zebra is horse meat (or donkey meat) and has a very, very strange taste. If you love the "weirdness" of mutton and goat, you'll probably like Zebra as its equally strange in its flavor profile in a different direction. With piri piri (chili sauce) it is just fantastic cooked medium rare. Also as fried fritters, its pretty amazing stuff. Every trip to Africa I beg for Zebra on the menu for at least appetizers.
Tilapia. Known by anyone, anywhere with a modicum of taste buds to be absolutely disgusting filth. American sold Tilapia tastes like potting soil (because they are in tanks eating the *$&% of fish in higher farm tanks above them). They live in currentless farms in American and the flesh is mushy and just disgusting. It has no flavor other than dirt and needs lots of sauce at some crappy Fridays/Chilis/Bennigans/RubyTuesday to choke it down. Now contrast this to REAL tilapia in Africa: Lives in rivers with strong currents so it is plump, meaty and not mushy due to muscle content. Doesn't eat the excrement of other fish in a tank so it doesn't taste like dirt. A truly marvelous meal in the wild state that is reminiscent of excellent blue gills from the North Woods.
Tiger Fish: Bony, but delicious. It is just like Northern Pike. So if you hate bones and hate pike, you'll hate Tigers. If you know what you're doing and know pike are one of the best eating fish in America, you'll know that Tigers are just the same way. Bony, but delicious if filleted properly or made into fish dip.
Duiker / Steenbok - Just fine. See Impala.
Doves/Pigeons/Sand Grouse/ Francolin/ Guinea Fowl - All awesome just like game birds everywhere.
In conclusion, while there are many opinions, there are many experiences. Do not rely solely on what is known to be "amazing" or "terrible" because it depends. See waterbuck above...best meals in Africa is my opinion but we must have had amazing good fortune killing the right bulls on the right diet near the right water. Happy eating!!!