It varies according to what you want. Do you want to trade or exchange cryptos?
In spot trading, you choose the buying or selling price at which you plan to execute the order at, and therefore, with a little technical analysis, you determine the buying and selling points, and from them you achieve profits by buying at a low price and selling at a fair price.
by using Convert you cant trade crypto in that way.
In spot trading, instead of exchanging cryptocurrencies at a specific price, you can choose the appropriate price with you and wait for some time until the order is executed in the order book, and thus you will get a better price.
It is true that Convert does not contain fees, but there are hidden fees, which is that the price of executing orders is chosen by exchange and it can profit from the price difference.
it is closer to say
spot trading: exchange 1 BTC for 101 USD with 1$ fees
Convert: exchange 1 BTC for 100 USD
You mean that the price on convert instead of the spot trading page is in a way it will not favour the trader and render the 0 fee to be useless, or to be in a way that using the convert will make a trader lose instead.
I have not used convert before, but this is what I found out.
Inchcknthe price of sport trading now and it was $2
See convert trading fee for BTCUSDT pair:

Like I said, the price is the same. You can also use limit order on the convert page.