Which broker should I use for buying US Stocks as a 20 y/o student?

Currently a 20 y/o student studying and looking to invest in US stocks. I'll be mainly looking at growth stocks.

Popular brokerage seems to be IBKR/SC. I'm not sure if I will be able to consistently invest as I am not sure if I am able to get a fixed income(IBKR monthly $3). SC also requires me to be 21.

My question would be what brokerage would you guys suggest I use?