I've been cubing a little bit now with Aligned Heart and it has been ... fine. It sometimes has it's high notes, but triggering from double spelling on a three drop is not trivial – best outcome so far was a game where someone got five monks from a trigger.
The biggest downside is probably, that it gets rapidly worse later in the game. Where Monastery Mentor is still a 2/2 prowess guy and also triggers when you just topdeck one noncreature spell, you need a little more to trigger the enchantment in the later stages of the game, like card draw or adventure creatures.
Take all that with a grain of salt, pretty limited experience here still.