I don’t have a specific favorite brand, I experiment with many beans, but when my coffee machine broke, I discovered if I grind beans somewhat course and make the coffee in a moka pot and add a tiny smidge of salt, it’s so nice I can drink it black (or with salted butter). As for tea, I add extra crushed ginger or citrus zest to my tea infuser and it’s very nice. I drink green tea with macha, can’t read the brand because it’s not in english, I’m up crap creek if they change their packaging.
My suggestion on how to find coffee you like to drink black is to visit your local snobby coffee bar and explain to the barista what you want. Order a few Americanos. A good coffee house with have multiple types of beans available on the same day. Try them all. If you’re using a “normal” American coffee maker, it might taste a little different when you get home. Experiment with different grind sizes and dosing. If it’s sour or bitter, something is wrong. I recommend staying away from anything from the African continent unless you really like funky coffee flavors.
My favorite coffee is from Central/South America (Columbia or Brazil). I usually brew with an Aeropress or French press. Spending $30 on a hand grinder and using whole beans will change your life.
I love Mount Hagen Freeze Dried Organic Coffee. Before you get disgusted that it’s instant (because most instant is absolutely disgusting) let me tell you it tastes amazing. So much so, I’ve got rid of all my coffee contraptions and now just have an electric kettle. Ive saved so much time and money using this coffee. Ready in 15 seconds. I’ve even had multiple friends switch over. Read the reviews on Amazon!
Edit: thanks for the teas suggestions! I’m always on the hunt for more ideas!
Try a blond roast, aka light roast coffee. I find they have a smoother flavor than a medium or dark roast and might be what you’re looking for. Also, if you haven’t already tried one, sample a nitro cold brew.