There is a huge disparity in how much benefit certain champions get from new runes.
It's pretty ironic when People think the new runes are significantly less diverse than runes and masteries isn't it? I'm finding a number of champions where literally nothing I can choose looks good to me. Too many of them are champion specific and there are so few choices compared to the sheer amount of combinations you could get with runes/masteries.
Let's take mages for example. I really don't see anything I like on Karthus for a damage oriented build. Can't take comet because you don't have a slow or CC ability to reliably hit it without making a much larger cooldown and mana investment(using W then Q) than other champions, I don't think phase rush helps me much for obvious reasons, electrocute, dark harvest and predator don't either. This mean I'm stuck going inspiration sorcery and have pretty much no other option(can't go precision secondary because it gives attack speed). Unsealed book would be great if revive was still in the game to bring back revive/tp/zhonya/ga karthus where you have to die like 7 times to be out of a fight, but I think you'll only get a very very small use out of it switching from barrier/exhaust/tp maybe once in the game to transition out of laning. If glacial were on spell hit as well it would be absolutely fantastic, but karthus, uh, generally doesn't AA past laning at all, and ROA is generally better than GLP in my opinion so item activates aren't going to get built to much either. The only things I really like on Karth are stopwatch and ultimate hat. I'd say Gathering storm, but games are too snowbally for it to be worth anything.
Meanwhile, anyone with an ability that even so much as slows is dominating with comet. It's absolutely too strong on long range mages like Lux, Vel, and similar champions. The problem is you're basically putting champion abilities into runes, so with the tiny number of runes there are, of course you can't make something for everyone. We really need another keystone in every category, or more raw stats, and at least one or two more rows in each tree so instead of a meager 6 runes, we can get 8 or even 10. I'd like closer to 12 actually. I don't care how much you weaken the effects of what's currently out there to do it.