What is Balance in WarmaHordes?

dey got tid of hils cuz u couldnt bslance models on dem if dey was 3d so it fixed now

I think either or would work. The most important part of balance is relative strength.

It's a different genre altogether, but if you compare modern YGO to old school, everything is a lot faster, more fluid, and also more conplicated now. It's the same balancing act, the pace is just different.

In other words - would you prefer if everyone had a 16" threat range and could trivially one round colossals, or would you rather have them capping at 11", with more prolonged battles of attrition rather than instant beatdowns?

Oversimplified, obviously, point costs, power, aim, defenses, synergy, threat range and scenario layout are all part of the puzzle, but I'm trying to keep it simple for the sake of clarity.

I would say that balance is always relative so there will be no absolute balance (expecially if many casters have a very overpowered feel to them and there is combos of spells and units).
Balance aspects are:
Faction internal balance: Are all options viable? To what degree? Are there clear winners and losers?
Faction vs Faction balance: Are factions dominating? Are factions weaker than others? Do factions have significantly less options than others?
Meta balance: What is being played, how well can your faction respond? How does this meta skew the list, can lists adapt? How much does the meta warp list building?

Of course you can never really achieve this perfectly. What you need for internal balance is some niches for Casters and Units to differentiate them. This somehwat achived by themes. On the highest level, probably still only the most important choices are relevant - but if that gives a playable game this is okay. Not nice for the stuff on the shelf but one unit too weak is better than one too strong. In Warmachine most things are pretty viable. Sometimes something can also fill a niche because your oponent is not used to it, or be weak just because they know how to handle it. In the faction vs. faction balance it gets more complicated because you have differend matchups advantages to a faction and disadvantages. Hopefully the faction identity does not give them too much of an edge against certain factions or too much of a disadvantage.
Problematic are choices that outcompete everything in faction and easily win against a lot of factions. Those need to be toned down for the game to stay interesting. Also it is ususally not desirable to have things that are too easy to pilot or that do not allow your oponent to interact with you. Haley 2 in Mk2 combined these aspects very well I think (except for ease of piloting if your oppent could reach scenario).

For the general game balance: I think it is pretty good. PP nerfed a lot of these "offenders" throughout mkIII. There is still stuff that feels overpowered, some Battle engines that become too good not to use or some Clockatrices and even Tharn. There is still stuff that is underwhelming. Most of these things are only "one thing" away from being okay usually or being back in line. Warmachine will always be a "hard" game, so you will always feel some struggle against what your oponent brings. But I think PP is doing a good job so far and as long as they keep pushing things back in line, the game will remain interesting but sufficently balanced (I hope). As long as you feel you have options, can be creative and are not utterly dominated be specific things, balance is good (enough).