Summoners
I feel like some summoner spells (other than flash, IMO that is balanced and is a great game mechanic as it is available to everyone) should be buffed. I feel like the summoner spell options for every role aren't diverse enough and some flat numbers changing could change that.
Now I'm going to list the roles and the optimal spells (realize that ghost is situational and I'm not going to list it but it can be more efficient than flash)
Top - Flash/TP Jungle- Flash/Smite Mid - Flash/Situational ADC- Flash/Heal Support- Flash/Ignite or Exhaust
Note that you have only two roles that really have a choice. Ignite is only optimal on one or two top laners or for cheesing.
IMO some base changes to numbers or some small changes to things like Cleanse and Barrier could make them viable for supports and top laners. I feel like in their current state TP for top, smite for jungle, and Heal for AD will be optimal in every situation given the roles nature.
Thanks for reading!