You do not have to do market orders, and on coinbase there is no fee, as long as you set limited orders.
Furthermore, what does it matter very much about which exchange, whichever one you can get onto and then of course your spreads would be farther apart if there is a higher fee in order to at least cover the fee.
I agree that you might be inspired to move some of your trading based on lower fees, which I did when I moved some of my trading from Gemini to Binance - but each exchange has its plusses and minuses - and even questions about whether you are ready, willing and able to link a bank account to the exchange, which options would likely depend somewhat on your origin country, too.
Coinbase has NO spread because of the way the fee structure incentivises bots to be market makers. The bots are some of the best I've seen, best in the world bots..
I like to place market maker trades myself because I like to trade inbetween walls, and the bots there are just too much competition for my trading style. It doesn't feel good..
I like to be on the high volume exchanges where that exchange is making the world market, or atleast have a close eye on those charts too.. Always watching a few..
I usually take a LOT of tiny stoplosses too so low fees make it a lot easier to get back out of a trade I no longer like the look of.. Which is incredibly hard to do on coinbase trying to get in with those bots..
I made a binance account for the first time last week when I was chatting with some group trading there, where I found that tool you all like so much actually, but I decided that I really didn't like the new shitcoins of the day trading there much and the group turned out to be really just trying to sell TA to pretty much puppets that would trade their TA..
I have a hooked up coinbase but I don't figure I'll need my bank account UNLESS I DO AWESOME TRADING!!
And about exchanges with no margin.. Then I can only make more BTCs when the price is going down..
If I have margin I can also make more BTCs while the price is going up! And down..
I'm checking out the usdt/btc on binance right now..
I might have crypto trader PTSD or something < made that up..
I really want back in there but I just haven't been able to bring myself to do it.. Probably causing my exchange indecision..