i can only see a few examples due to the fact i have not played all the champions yet. But ill list a couple i have noticed and see if anyone agrees or can find any others that should be fixed in a patch. The ones i am going to mention will not be major changes that are needed just a small tweak to make them as fair as other ulti's of similar style.

1st up. Miss Fortune. the smallest of auto attacks can cancel her ulti. like really yet Gangplanks continues after death. i think that either take the cancellation effect away due to her " temporary blood thirst and adrenalin rush of such a sweet looking ulti " or shorten the reuse timer of her ulti on an interrupt.

2nd. Akali not sure people may agree or disagree. But i have had it a few times where i use her ulti and die in mid flight from a random attack. should it be so that i can not take damage from an attack once i have hit my uilti. Dot damage that has started prior to ulti obviously still stands.

3rd aaaaa i thought i had another but cant remember at this point of time. But i would like to hear others feed back on small little things that will help balance out other champions ultis.

Both of those are fine as they are.

maybe for Akali its fine as is. But MF is already considered the weakest ADC and im continually told not to play her due to her being weak. maybe if they fix her ulti she could stand up to be a choice pick in ranked matches again. And im not sure who but i know there is another one who gets there ulti interrupted as well.

The Ulti isn't the reason she's not a super strong AD carry. And it can't be interrupted with just an autoattack.

The reason she's not as strong as other AD carries is she's got Vayne's rather ho-hum range, without the damage you get from other champions with that range, like Graves and Vayne, and she has no escapes other than an AOE slow and her passive.

What she needs is a stronger steroid.

I mean, Vayne has her silver bolts, which do percentage of maximum health as true damage every 3 attacks + a flat amount. That is preposterously strong. And her ult and Q are both steroids, and her Q + E is a very strong escape, or Kill Securing form of CC.

MF's impure shots do a small amount of magic damage every shot, and she's got an AOE slow. Ho-hum.

Auto-attacks don't interrupt MF's ult, she wouldn't be played at all if that were the case.

Channels are cancelled only by disables/repositions.

If you mean any auto-attack can kill her... well that's how its meant to work.