Leaving all crypto on a trading platform sounds pretty scary. I heard this is too risky, so it might depend on your attitude, the amount and type of assets, a country, a platform, etc. and probably should be considered on a case-by-case basis. But as a rule of thumb, when it comes to all the crypto you have, the safest way to keep it is in a cold storage they say...
I prefer Ledger Nano S.