No.
HMM > v3: sucks
KB: great

What is v3?

version 3
HMM > v3 - all Heroes titles over version 3
HMM3 was the last decent heroes game; still playing it to date with WOG and custom maps. HMM4-HMM6 just sucks.
King's Bounty delivers in every sense. Its only drawback is the replay value - but I can live with that because I do not replay games more than once a year.

HOMM VI didnt keep me for long, played few campaings thats all. Thats far behind KB

Ah well, different tastes. For me, HoMM V has surpassed HoMM III in single-player, the factions were far more diverse and the skill system with its perks the best of any HoMM game.

HoMM IV (with Equilibris) is for me the best Heroes game, but it capitalized on the series RPG elements so it's not for everyone.

HoMM VI has not managed to hold my attention either.

Yes, it's all about personal preferences.
HMM4 would have been all right, but the skill system was terrible (IMHO).

I have played all of these games; here's my quick take.

First of all Heroes II/III/WOG were the best games in the series; like King's Bounty I would just want to play "one more turn". For HOMM VI, I almost feel like I'm forcing myself to play it. I enjoyed the first Necro Campaign but find myself losing interest in the 2nd one. All of the modern King's bounty games I couldn't wait to keep playing, and have done most of them multiple times.

My 5 year old son always sat next to me playing "the horse game" (his words) but lost interest quickly watching me play HOMM.

I am a long time HOMM fan, played the very first one, loved the second one, third is probably my favorite. Then 4 came out and it was an abomination.

So Ubisoft, whom I hate, is the new publisher of course and they are having their developers churn out shit. HoMM VI looks a little better than the V and definitely better than IV but still KB is waaay better. IMO of course, YMMV, etc.

"Just one more turn" is exactly how I feel while playing Heroes III, King's Bounty TL/AP/Cross Worlds.