I rate KB as one of my top 10 or perhaps 20 PC games of all time. I spent well over 200 and possibly 300 hours playing it before I finally got bored. I will buy the expansion the moment it is available on Gamersgate, and probably any games Katauri make in the future.
HoMM V, I bought Tribes of the East a few weeks ago and downloaded a patch which gives the earlier campaigns as well. On the surface there appears to be a fair bit of similarity between the two, especially in terms of the combat. HoMM V has more of a strategic layer, but it's still pretty simplistic.
The first two missions of the ToE campaign were a lot of fun and quite difficult on normal difficulty. I found the first campaign of the original HoMM V very easy and quite boring. After about 20-30 hours of play, I stopped playing and started playing something else. (Space Rangers 2: Reboot).
KB has the x factor that HoMM V lacks. I also don't like the traditional mission structure in HoMM V, which requires you to build up your towns from scratch every mission. This was also a problem in Disciples 2.
So I guess I am saying KB >>>>>>>>>>>>>> daylight >>>>>>>>>>>> HoMM V
