Tier 1: Pokemon that sorely needed Mega Evos and benefited from them drastically
>Mawile
>Pinsir
>Kangaskhan(During her 15 minutes of fame)

Tier 2: Pokemon that may not have needed the Mega Evo but have benefited from them drastically
>Ampharos
>Abomasnow
>Aggron
>Absol
>Venusaur
>Gardevoir

Tier 3: Pokemon that kinda needed a Mega Evo but didn't really benefit much from having them
>Banette
>Houndoom
>Medicham
>Manetric
>Blastoise

Tier 4: Pokemon that really didn't need a Mega Evo + Pokemon who are actually more useful than their own Mega Evos
>Scizor
>Heracross
>Gyarados
>Aerodactyl

Tier 5: Pokemon that did not need a Mega Evolution at all
>Tyranitar
>Garchomp
>Gengar
>Alakazam
>Blaziken

Super Special Bottom Tier: Pokemon that only have Mega Evos as a fanservice to furries and Genwunners
>CharizardX
>CharizardY
>MewtwoX
>MewtwoY
>Lucario

Also discuss what Pokemon you would have liked to have seen get a mega I guess