Comparing Base Caster Classes and Modified Casting PrCs

[Endarire]

Spellcasting progression is very powerful in 3.x (and, by extension, Pathfinder) and is likely the game's most powerful non-infinite ability.

Assume for a moment that instead of the current setup, all PrCs that current advance casting now advance casting at every level except the first. Nothing else changes. How does this affect the desirability and power of PrCs? How viable is going straight Cleric, Sorcerer, Wizard, or otherwise? What classes are most affected by this change and how?

[QuickLyRaiNbow]

If every class is equally affected, then I don't think much changes. The biggest gap in spellcasting is the divide between having 9th level spells and not having 9ths. The difference between casting as a Wizard 19 and a Wizard 20 isn't, I don't think, all that big a deal. You'd pick the class features every time, I think. Right now, though, we get to have our cake and eat it too.

[Andezzar]

Also most PrCs with desirable class features have 10/10 or 9/10 casting already. There might be one or two that previously were undesirable but with nearly full casting may become a lot more interesting. Master Transmogrifist for example.

[Extra Anchovies]

Basically every 5/10 caster would be viable. Warpriest, Bladesinger, Entropomancer, Mindbender, Greenstar Adept...

Also, Spellsword would be good. That's enough to make me tempted to implement this, because I so wish it was viable past a 1-level dip. Of course, that's mostly because I'm so enamored with the accompanying artwork (https://i.warosu.org/data/tg/img/0354/99/1413214414739.jpg). It was a very close second to Bone Knight for my choice of avatar.

Looking at the art for both, I guess I like heavily-armored characters standing up with swords planted on the ground. Huh.

[Andezzar]

I like my gishes more lightly (http://vignette3.wikia.nocookie.net/warriorsofmyth/images/b/be/Ex_5N_KnightPhantom.jpg/revision/latest?cb=20130611002547) armored (http://www.rolroyce.com/img/DDP/Clases/CampeonAbjurante.jpg).

[Extra Anchovies]

I don't even know why the Abjurant Champion is wearing armor. He's got mage armor up! I guess it's for armor properties, but he'd be better off with padded armor for that.

[Andezzar]

I'm just as confused about the physical shield. Shield is one of the few spells that actually work better for abjurant champions.