Well, i will say cold storage is prefferable when you are willing to hold your crypto for a long time. cold storage means storing your crypto in an offline device especially when you dont want to access it for a long time.it is the safest measure that can be taken to disallow hackers from hacking into someones privacy and clearing what doesnt belong to them.

mostly what i use to store my cryptos is papper wallet which is one of the two means of cold storage. i use this over hardware wallet because i will totally be in control of my account. it gives me the opportunity of printing my public and private key on a piece of papper and no one will be able to access it  and i wont panick over hardware malfunction.

The exchange platform to me is only used for the cryptos i intended to trade on daily basis.i dont leave my coin on exchange as such because private key is going to be saved on another server which makes it more susceptible to hacking just like what happened to bitfinex in 2016 where more than $70million worth of bitcoin was hacked.

Cold storage has been the safest for me because its offline compared to exchanges that are online. It can never be hacked.if the keys are kept well,ones crypto can lie in it till eternity.