Actually This Is Very Important Question Topic And I Hope This Questions Answers Very Difficult By The Way I Always Suggests Good Wallet To Store Your Bitcoin BTC I Think Better To Use Safety Blockchain Wallet And Coinbase And If Thinking Little Trade Sometimes Than You Can Use Binance And TrustWallet.
Using an exchange as a wallet is not recommended, same as closed source wallets that the code can't be verified to know how the keys are generated or if the developers are doing anything shady. Trade on exchanges and move your funds into your self custody through open source wallet like Electrum and Bluewallet, they are both recommended. You should also back up your seed phrase properly, but even Electrum and Bluewallet are both hot wallets, but you can either set it up as an offline wallet on an airgapped device if you like, or you buy a hardware wallet, that's it you want to hold a huge amount of BTC for long term.
Are you just holding long term? Because if so you don't even need a wallet. Bitcoin isn't stored in a wallet, it's stored on the blockchain. A wallet is just the software app you use to make transactions. If you're just holding long term, ie cold storage, just make an address and send your bitcoin you bought to the address and keep the private key and the address somewhere like a paper wallet. No need to download anything until you want to move that bitcoin.
This is in form of a paper wallet, but it is not recommended for newbies who don't have so much Bitcoin knowledge like OP. But to generate the address and seed, OP still needs a wallet and a good one too to be sure of the keys. If OP deletes the wallet software afterwards and writes the keys out, they have one less backup, the wallet software they use can be used as a backup to gain access to their funds if they lose the seed phrase or keys they wrote on paper.