Hello! I'm so glad you're setting up a tank, I set up my first one recently and I really enjoy it. Keep us posted on how it goes!
Personally, I think corydoras make a great addition to any tank. You could have a little schooo of them and I'm sure you'd enjoy them. I recommend getting 6-8 and choosing one species. I am very partial to panda corys, but there are tons out there you could check out. They're peaceful bottom feeders who do well in almost any community tank. I have some and I adore them, they're so wonderful and they have their own little personalities too.
I think tetras are great, too, but they're not my favorites. I have some candy canes (really quite pretty) and they're cute, but I'm going to trade them out for some platies (I love those little guys!). Livebearers like platies, mollies, or guppies are another option, but you'd have to take into account how fast they breed LOL. I'm trying to breed them, so that why I decided to get them, but they have a ton of fry. You could always get all females so they wouldn't breed, but if you want babies and both genders, one male to every two or three females.
I don't know much about any other fish, but I hope this helped.
Best of luck,