I know this is super late, but who cares. Illusion & alteration are powerful... Crazy powerful... 'Specially at late game. Its very easy to grind for illusion too. Just spam muffle or hit your companion with a courage spell constantly.
Alteration is powerful for one reason mostly: Paralyze and Mass Paralyze(Or was it Mass Paralysis). You can literally just walk in, slap everyone with paralyze and chill as you take them down one by one. Its only weakness is that you can't use it against: Atronachs, Automatons, Dragons, Dragon Priests, Ice Wraiths, Mammoths, Skeletons, Wisps and Wispmothers.
But if your opponents arent those? Easy, you just wreck everything xD. 'Specially with a 100% reduction to Alteration so you can just spam it everywhere. Its quite funny for me to watch Creatures frantically trying to kill me as I walk somewhere and just cast Mass Paralyze and then watching their bodies go limp as I slowly kill them with a fork.
Illusion is quite powerful too, with a high level in illusion and with perks. You may find yourself laughing as you chase a dragon priest who got hit by fear.