I enjoyed them all for various reasons including the diversity in the locales and fighting different nationalities. I wish Sabre Squadron could have given us a little more in that department.
*I know that most of the ops in H&D 1 and 2 were not undertaken by the real SAS*
With that disclaimer, I think the Challenger mission should have been expanded upon in the Castle level. I enjoyed the scripted sequences and the whole thing gave me the Where Eagles Dare feeling. I would have liked the interior of the castle however to have been really cavernous and for it to have taken place at dusk or something to give a more ominous feel.
I also loved Liberator because it was the only level where that old H&D feel was somewhat present, particularly in the last level which equals the feel of Ammobox. That map was quite large and you could see great distances like in the old one.
Liberator is probably my favorite as it contains all the elements I loved in the first one. First it is in Eastern Europe. I realize that the SAS didn't op in this theatre but I love Eastern Europe as it provides a really beautifully sinister backdrop as being in the heart of enemy territory and having really dark forests, mountains and the like. I'm a sucker for Yugoslav locales in particular. The first H&D captures it perfectly. A vareity of different gameplay styles are here including urban combat, stealth and open terrain. The final mission takes all with its huge ominous atmosphere. I love watch enemy patrols. The Russian twist was classic H&D. Rescuing Trebissky was brilliant and I love killing the power before going in. The map reminds me of the Italian train station in the original. It was just a really great campaign/mission. I would have liked the town to have had some civilians at least or something. The ability to recon its outskirts and make the infiltration would have also been stellar.
As for the combat heavy levels like the Anthill, Chesnut and Overlord, more enemies or at least more atmosphere is needed. It was an incredibly linear level and I felt that the Prague level in the original should have been the template.
Snowball was enjoyable as I love winter missions and stealth. But the atmosphere of the original Norway missions is still MIA. I too hope H&D3 will address this
And as a histroy buff willing to suspend disbelief, SAS ops before the SAS existed is still hard to swallow They could have started the game in Africa and then done a fantasy Norway op. *The SAS actually did go to the country but only in 1945 to help disarm remaing German troops.
They Dared and Won..... And They Were Hidden and Dangerous.