i do both because i trade with some coins as well

From the point of view of what's more secure I think exchanges and open web wallets are the same. It's easy to hack both. Desktop wallets are little bit more secure but still not perfect. But where to keep crypto depends on your aims.

Crypto storage today is a dilemma. Many people are hacking wallets and losing crypto. The solution is to use Ledger Wallet. Absolutely 100% security but it also has some disadvantages: can not trade flexible exchange, it is only 1 place. However, the trading exchange today is also quite high security, you can store on it as: binance, huobi, kucoin, ...

I use stock market sites to buy and sell. The stock market sites are more advantageous for quick transaction in Piayasada. Wallet is better for long-term investments.

If you want to trade coins/tokens is better to save in exchanges. My suggest don't keep your assets in an exchange for long term. Because recently many exchange have been hack. And if you want to invest, i suggest to save in the wallet.

I use both, but you can trust the wallet.it is very easy to use and I have never experienced any hardship or acceptance until now.

Funds can be stored on the exchange for rapid trade in the case if the rates have changed dramatically in any direction (up or down). But this is more suitable for those who invest for a short term and focuses on courses and trading. So is better to keep funds in a cold wallet, or on an offline wallet, but only buy them from the manufacturer or an authorized representative, so as not to buy an offline wallet with a virus, etc.

Not safe to keep coins on exchanges, not heard of mtgox?

It seems to me that in this branch already says enough that you do not need to keep your money on the stock exchange accounts in the long term, so I do not advise you to do this, you definitely will be able to lose them if the stock exchange wants it.

You can keep your tokens on exchange, but in such case you should use Google authentication.