I don't really go for 'brands' of coffee. I ride to my local roaster or sometimes order from Has Bean, and buy a particular variety from a particular plantation. What I buy depends on how the flavour is described by the taster(s).
For the morning espresso I tend to stick to a few Brazilian-grown varieties - the few that I order most have a flavour that can be described as one or more of the following: chocolatey, cocoa, caramel, toffee, honeycomb... it's a nice familiar taste that I can't get enough of. I could stand all day just inhaling its aroma just after it's ground.
For general drinking I like to taste any good coffee. I like quite a couple of African ones I tried recently. There's a really nice Kenyan one that I tried, really bright, kind of fruity (dark grapes) acidity, very liquoricey and a really nice thick, chewy mouthfeel. And an Indonesian variety that I think was slightly fermented, and had a very prominent over-ripe banana aroma, almost alcoholic flavour. Like fortified wine but with a very smooth, fermented fruit flavour... I definitely wouldn't drink it every day.
I really liked Guatemalan elephant bean coffee. I can't even describe the flavour except it was almost like a ball on the tongue. A nice thick mouthfeel, really pleasing gentle sourness, sweetness, dark earthiness... just super good. The last batch I had was over-roasted though and tasted like burnt toast...
You can play it safe and offer one average-tasting coffee like Lavazza 'espresso' but if you offer a few really distinctive varieties then your customers will take more interest. If you have ten varieties then there is the possibility a customer might make a purchase nine times, just to try each variety once. It helps if you take a real interest in coffee too.
This helps with tasting: