I never played the original, but Half Life 2 was genuinely just really fun and had a great story, writing, and characters. It had cool action set pieces, sections that scared the absolute shit out of me, and plenty of memorable moments. It's maybe not the best game ever or anything, but it did so much right and had so much variety that it's certainly stuck with me as a sci fi nerd. It helps they left us with a cliffhanger ending for basically forever.

Alyx though? Good fucking god. That's one of my favorites of all time as a fan of half life. Playing through that in VR was fucking magical. There's genuinely nothing else like it and it's so well done. All the things that made Half Life 2 great, but you get to immerse yourself in it.