I haven't tried to play hl1 again, but Morrowind is amazing and the modding community is amazing, I clock a good 200 hours every time, and I still went over a hundred thirty on a vanilla playthrough four years ago.
Just so I can say this as many times as possible since I'm still crazy about Morrowind, the modding community adds things in Morrowind like fantasy setting lamp posts between cities with ambient gradient light, high res night sky, or even just distance relative water sounds from rivers and waterfalls, small touches that make the entire game seem new.