Good app to buy and sell

[Pmalek]

I am looking to buy around 10-15 type of coins and keeping them for long term 2 years +

Whichever exchange you pick make sure that all those coins are supported and traded there. Since you mentioned that you are leaning towards Binance have a look if the coins you plan to buy appear in the following list as well as the fees that apply to them.
https://www.binance.com/en/fee/schedule