This is a really subjective opinion so it's hard to describe. I think things started to go south when it mattered which hero you had. It's really bad when you have to pick a certain hero and build him up a certain way in order to win a scenario. That's not strategy, it's figuring out the secret, and it's not fun. I don't want to have to unlearn a skill or pass up a perfectly useful skill just for the slim chance that I might get to Ultimate, and I can't win the scenario without it.
The issue described above isn't all the game's fault per-se. IMHO it's mostly a problem with the designer of the map and not stating in the map description that this is an RPG map. If a map is designed & balanced around normal heroes with reasonable skill sets then you shouldn't run into this problem. Anytime I design a map for myself / friends / etc. I often do "weeks" of testing to make sure it should work as expected.
My ideal is the H5 skill system without hero-specific specials and no skills being better than others. That means no second- and third-tier abilities and certainly no ultimate skill. No heroes or skills should have to be banned in multiplayer. I think maybe we can keep the unique skill for each hero type but it's important that those not be any stronger on balance than the common skills. If we can achieve those goals, we'll have taken the focus off Diablo 2 style hero builds while retaining the interesting variety of hero skills that makes the Heroes games unique.
Your requests are quite reasonable but I prefer a middle-ground between your position and H4/H5.
I'd like to see:
-- Heroes that are different from each other. Different starting skills [all need to be reasonable skill sets] ; bonus abilities ; different starting spells all sound reasonable to me.
-- A Hero's "bonus" should provide a very small bonus. For example maybe a bonus "stat" point [+1 SP / +1 ATT / +1 KN / etc.]? Maybe a fixed +1 ATT / +1 DEF to a specific creature type? Maybe a bonus move of +2 units? Maybe a +3% to Necromancy percentage? .... IMHO the bonus should certainly be less than half the "ommph" of a skill at basic level.
-- A Hero's starting skill set should always be a good & reasonable skill set even if it's duplicated amongst different heroes.
-- A Hero's starting spells should be reasonable. I wouldn't want a hero to start with any spell over L2. Even then I'd prefer just a bonus L1 spell.
-- I don't believe that there should be an "Ultimate" skill per se. I certainly don't want to see a repeat of the H5 ultimate. If you have an Ultimate though maybe any faction hero that has maxed out all their skill & ability slots automatically gets that faction's version of the "Ultimate" skill. This way you can still choose whatever skills you want for the map without being rubbed the wrong way with the game & map maker leading you by the nose and forcing your decisions.
FYI: I don't mean to flame or "dis" your opinions. They are reasonable. I just "prefer" a slightly different set of features.
I agree 100% that:
-- All skills && abilities should be balanced against each other. There should be [as much as possible] no lame skills or uber powerful skills. It should be OK though if certain factions find certain skills more useful ... I.E. the Necromancy skill should be more useful to Necromancers than other factions
-- There should not be any heroes that are significantly better than any others [of the same faction] at any point of the game [early, mid, late]. IMHO some developer was on crack when they thought Deleb & her bonus was a good idea