As we all know, the golden-age era of spellcasters having access to spells like Permanency is now over with the arrival of 5E. I am now DM'ing a top-tier campaign, and several of my PCs are casters who have requested a way of making several spells permanent.
What I have found so far
I have done some research and have found a few things which might help give direction to this.
There is a homebrew 5E version of the Permanency spell on the unofficial D&D wiki, but I don't feel like it's quite complete, and there is nothing for concentration spells.
Since Wish doesn't have spell permanency as one of its guaranteed effects, I'd prefer to omit it as a solution. It would probably have drawbacks, mostly with its reliability (using it this way is a 33% chance of no longer being able to cast it), and also because several casting classes do not have access to it.
As far as having a permanent effect on a PC directly, I was thinking of having PCs with access to Clone create a clone, but with a longer casting time, and having to cast the spell they want to affect them permanently a certain number of times. The original then dies, and is transferred to the now enchanted body.
I am looking for ways, other than the casting of Wish, to add permanency to spells.
What is a good answer?
Good answers to this question will follow the Good Subjective/Bad Subjective rule. I am looking for answers from DMs who have tried granting players some form of permanency in their spells.