I want also add to the above, that converting between cryptocurrencies eats up little bit more commissions, than just buying a cryptocurrency in an order book on Binance exchange. So I always use the second option.
are you sure about this?
last time i checked the convert method was there to only let users buy or sell at market price instead of placing a buy or sell order at their desired price and wait for it to be filled. that means the commissions should also be the same.