30 gallon tetra tank?

I have a 30 gallon long tank which i just finished cycling ( i know how to cycle a tank, done it before) and I wanted to know what types of tetra i should put in it and how many of each breed. I dont want hard fish to take care like ones that die easily. Good hardy tetras. keep in mind that i already have 3 platys and 5 cory cats...Thanks in advance!!