I mainly use the 2.1 ROM as it always opens with the draw bridge scene which seems logical and some other nice enhancements. Yeah the original was all over the place on what scene was coming next and of course the reverse scenes. The arcade always cranked it up to hard settings so split second timing was required. It definitely seemed like they incorporated a finite set of scenes for each "section" of the game.
If you have access to the HD version it looks much sharper than the box set and runs great on the Pi 3.
Dragon's Lair ROMS
Dragon's Lair Enhancement ROMS
For people who know the original game very well, F2 is the gold standard. For 100% authentic gameplay, there is no substitute.
For people who want an 'improved' version of the original, DLE 1.1 is best. It adds the drawbridge scene, and eliminates many quirks and illogical moves and timing.
DLE 2.1 is the game as it should have been made to begin with. If you aren't very familiar with the original, this will provide the best play experience. OTOH, if you know the game well, and don't want to 're-learn' it, it will probably just frustrate you.