Coinbase Pro, Gemeni, or Binance for a total newbie?

Sorry if this gets asked a lot. I'm totally new to investing in crypto, and I want to invest a pretty small lump (~$500) and hold it for a while, because I'm certain eth is only gonna grow from here at least long term. I probably won't be investing much more for a while, I'm mostly doing it to scrape up some neat beer money. Seeing how small of an amount i'm messing with and given how new I am, which app would you guys recommend for me to buy with?