Where is it more convenient to trade a burst coin, Bittrex or BTDEX?
It depends. If you have an account on Bittrex, its probably easier. But if you do not already have an account on Bitrex, you will need to provide KYC info and wait to be autheticated.
Some other considerations are:
BTDEX requires no authentication.
BTDEX does not require you to deposite you funds in an account outside of your control.
And you may get a better price on BTDEX. You will certainly pay lower fees on BTDEX.