I've been doing a combination of both, you could say. I like to pop the bottom of the canister off with an old style beer bottle opener, has round opener for bottles on one end and sharp opener for popping hole into cans on the other. Then I leave the film in the canister on the spool. This reduces the friction between the film and the can opening/felt so that the film just feeds right out onto my spool with minimal tangle. I'm working in a film bag and when you pop the can open and let the film out it wants to unspool and fill the bag. It can be a pain to get the film in the right orientation so it doesn't jam feeding into the gate on the reel. If you are in a room you can just stand and let the whole length of the film dangle in front of you while you wind it onto the reel, but in a bag it's different.
Also, it's easier to trim the leader to just the right shape to feed onto the spool if you can do it in the light. So I prefer it out, trim it rounded square, pop it in the bag, pop the bottom and gently unspool onto the reel from there.