Considering that they are quite far apart (in the warped time of video game releases) and being quite different games, is that really a fair comparison?
They're both FPSes, only NOLF gave you more gameplay options. And just the fighting in itself is much better than in HL 1 and 2. Why wouldn't it be a fair comparison?
I don't think HL1 and NOLF are the same type of game. HL1 was all about survival, science, and a weird alien invasion. The atmosphere was completely different, the story was completely different, and the theme was completely different. The shooter aspect was the only tie, and on that HL1 beats NOLF. NOLF had great shooter elements and lots of innovations HL1 didn't have, but in terms of pure FPS style, HL1 took the cake, IMHO.
And HL1 beats the socks off HL2 - that game was just more of the same, but somehow also less of the good same.
My list of all-time favourite FPS's so far would be:
Giants: Citizen Kabuto
System Shock 2
Deus Ex 1
No One Lives Forever 1
Half-Life 1
NOLF1 had better AI, had location based damage, and better level design than HL1. With this in mind, how can you say that the combat in HL1 was better than in NOLF?
Also, my list:
No One Lives Forever 1/2
System Shock 2
Deus Ex
Thief
AvP
Quake 1 multiplayer