Personally, I would like to be just a magic user(mage), clerics would be paladins and bards would be reworked as half casters.
Then with subclasses can be worked out as White mage(healer), Black mage(necromancer), elementalist/invoker, conjururer/summoner, green mage(druid), mindbender(illusionist/enchanter), kineticist, antimage/abjurer, etc...
All could learn all spells, but they would learn them as wizards now via spell book.
Sub class features at 1st,2nd,6th,10th,14th,18th and 20th level should be enough to make them a lot different from eachother. Also with free bonus spell depending on sublclass and spells chosen by character.