If you are starting with a open end drum, you can go either way.
If you want to use the lid that comes with the drum, it is easier to get an open top with the lid. if you get a closed top drum and want to use the lid, you will need to cut off the top below the bead, reinforce the cut drum edge, refit the lid, swell the drum edge below the bead etc...it won't be worth it.
Whip It Off, Chambers!
"perhaps...but then again...maybe not..."