Hmn, I love Faith, and I think she would've fitted in on either show at any point, great chemistry with the two leads
But d'ya ever notice how on 'Buffy' nobody's allowed to take the spot-light away from Buffy herself. Angel isn't really that competent in S2 until he goes evil, then he's suddenly a match for Buffy in a fight. And in S3 he's weak throughout a lot of the show. until, because he's getting his own show and moving on, he gets to be kickass near the end. ('Earshot', Choices' 'Graduation Day')
Also Spike, after he goes 'good' becomes much less effective, almost laughably so to say this guy almost killed Buffy a couple of times, until well into S7, when he becomes...*sigh* 'her strongest warrior', or a least close as to how tough he used to be. ('magic trophy victim coat!' 😡)
So Faith, wouldn't have been as effective on 'Buffy' because its Buffy's show, she's the star. Until that changed I really couldn't have seen her as a regular, she's a slayer, she should be tough.
(It's worth noting that when Faith was on Buffy, when she's not a badguy, it was to show qualities that she lacked that Buffy didn't, caution, adaptability in a fight, balanced approach to slaying, leadership, etc. The focus was usually still on how Buffy was the better slayer)
Having said that, the perfect season to bring Faith back to 'Buffy' would've been S6, since it's the darkest, everybody is screwed up, I think she would've fitted right in and wouldn't have upset the balance/dynamic of the show that much, then she could've stuck around for the whole of S7.
What, a man can dream. 😀
On Angel, definitly. 🙂
The whole point of 'Angel' wasn't about him being the most powerful character on the show, it was about him being unique, a leader.
In S5 we had Illyria, a hugely powerful Old-one, wandering around and Spike (who is, physically, Angel's sort-of equal) there, and it didn't feel like Angel was getting side-lined or anything. It worked.
Throw in superpowered people like Gwen Raiden and Gruesluugg, and Angel was never considered 'easily the most powerful character on the show'.
When Faith was on Angel, she was the slayer, and shown to be incredible powerful, still a flawed person, that Angel could've activily helped become a better person.
Faith could've fitted in to Angel right from S2 onwards. Man, that would've been sweet. 🙂
Her helping with 'Angel-less' Angel investigations, freaking out over little- vampire baby Conner,', bonding with Wesley (slowly) and Gunn (a lot quicker), maybe having an acual 'girlfriend' in Cordy (who has some similar personality traits to Faith- straight forward, pragmatic, etc) or Fred.