I constantly go back and forth between preferring HL1 and Black Mesa.
Ordinarily I'm an OG purist and the AI is so much better in HL1 but god playing both several times each makes you feel a bit let down with how small the HL1 areas are in comparison. Like Forget About Freeman has this massive battle where the HECU keep pouring out at you and then you play HL1 in comparison and it's just two guys standing around and a tank. Of course I don't even need to mention the Questionable Ethics lobby fight that was so memorable even when a dev played HL1 recently you could see him confused that there wasn't an HECU ambush in the original

I'm so bipolar on what the better game is