I have few of my clients on exchange wallet because I love to have it in the first reach so I can trade it fast if I need, but most of my coins are on my hardware wallet that are secured more than anything else.
I know saving it in hardware wallet will be much safer, for a long-term investment, of course I keep my coin in a hard wallet,
but I do trade also, of course I will save a few percent of my funds in exchange, to make it simpler when I use it to trade