My recommendation a for PC-friendly version of lycanthropy:
Let them wild shape (as the druid ability) into the animal their lycanthropy is associated with once between short rests (or prof bonus times between long rests if you must). No enhanced senses in humanoid form, and no regeneration or infectious bite in humanoid or animal form. You get your normal stats, or the mundane animal’s stats, that’s it.
Make hybrid form an involuntary transformation that happens in response to a specific trigger - specific phase of the moon is a classic one, but it could also be something like taking damage from a silvered weapon, or whatever else you like. In hybrid form (and only in hybrid form) they gain the regeneration and the infectious bite, but they lose control as the beast drives them to hunt, and to spread the curse. Maybe let them make a save to temporarily gain control or something, but the idea should be that this is something the PCs have to take precautions against. Chain your friend up in an isolated place once a month, or don’t let them carry silver coins or whatever.
The monster version remains for lycans that embrace their curse. If a lycan gives in to the inner beast and lets it take over, they (or rather, the beast) gains greater control over their powers, being able to shapeshift into any of the forms at-will, and if you want, they can retain their regeneration, enhanced senses, and infectious bite in all forms (though I personally still prefer those to be form-dependent). However, the distinction between the humanoid and the beast erodes away. If you’re using alignment, the lycan who embraces the curse shifts to the alignment associated with the lycanthropy (also it should go without saying, but no lycanthropes should be a Good alignment if you go this route. It’s supposed to be a curse, and a character who embraces it should not be suitable as a PC). If you’re not using alignment, they are consumed by the drive to hunt, kill, and spread the curse.