I agree with the Sivir points, but want to add on: I actually feel that Sivir's ult affecting lane minions to be useful. I've even been in the center of our base and timed all 3 waves spawning so I could ult as Sivir and send all 3 lane waves ahead with the movement boost. I also honestly feel I helped turn a few games around with a well timed ult, allowing my team to chase down and catch out 2 enemies, allowing us to plow into the base for the win. It's not really so much combat orientated anymore, I just consider it an objective buff that you don't have to kill a monster to get. Pick this up, with a Sona, Talisman, Baron buff/dragon buff, and you basically achieve an old loved win condition: winions. You literally create situations where all your team's champs serve as are bait to lure the enemy out the base for Super Minion ulted Baron angry guys to win for you. One of the enemies notices, they ping, even if anyone does retreat allies move to the exposed area: ect ect.
For the longest time (back before the maokai's reworks, like when his ult was where you placed it) I never would put a point in Maokai's ult at lvl6, I'd lvl something else up. I had experiances where people wouldn't use the area. They'd walk out of it, either avoiding it like they thought it was an enemy spell, or expecting it to do dmg to the enemy. Obviously I had games where yes people knew how to use it, but I just felt it was a waste of mana.
Soraka's new e. Aside from a low mana cost stack towards her stun, Annie's e is sorta useless/not really worth using as intended. It's meant to give her a boost to armor and magic resist, and burn enemies that hit her. Newb players (myself included) would be led to believe this makes her tankier, where you'd want to entice people to auto attack you while its up. This doesn't turn out to be the case, it's not like garen's w, it's just a way to turn a 3stack q into a 4stack stun mid flight or stack inbetween roaming fights.
Ashe's e actually has it's main use in the gold increase, it's a tool meant to reward players learning to last hit, it encourages them to do this with extra gold, a skill they should keep with all adc's. An experianced player can also use this even further, like a free avarice blade. Also the vision helps alieviate ward pressure on your support. And if your team ignores your "MIA" or "DANGER" pings, sometimes tossing the e to SHOW the enemy is enough to convince them. I hate pinging for incoming ganks, only to have an ally die and then rage, literally, WHAT NO MIA JFKADAIE%u#@@"