Well, you'll probably get a lot of answers here, so I won't worry about giving you misinformation. You'll have to select the proper answers for yourself.
Which is also true of the beans you use for espresso. It's basically up to you. I remember being irritated by that answer when I asked the question on a.c. the first time about 6 or 7 years ago. But it's true. You can make espresso out of any bean that you can grind. All that really matters is that you like the taste.
You can us SOs (single origins, ie. not blended) or blends. You can buy blends or blend yourself just by mixing various beans that you have bought. Some blends are based on Brazilian beans. Some on Columbian. You can then add Central-American beans, Ethiopian, Indonesian or others to that base or you can begin with a different base.
The one exception is Kenyan. Many people seem to believe that Kenyan beans are not suitable for espresso. I have not verified that personally.
Italian blends almost always contain 10-20% Robusta to add an earthy character and more caffeine.
Most people (well, me anyway) prefer a somewhat darker roast for espresso (full city or darker).
None of these recommendations are legally binding. You can use whatever tastes good to you. If you like a lightly roasted Kenyan then enjoy it and don't worry about it. The whole trick is to try different beans and find out which ones you really like.
Another attitude one can have is to try to verify that beans others say are good in espresso really do taste good. Just like trying to verify that white wines usually taste better with fish than red wines. If you try and say, "Whoa! That really doesn't taste good" then you are all the richer for it.
If, on the other hand, you come to the conclusion that you still prefer something that others say they don't like, who cares? It's you drinking it.