Uhhhm, Rick never fought against Alpha, at least in the show, he "dies" at the end of season 9, alpha's first appearance is season 10. Can't say much for the comics, haven't read them yet

Better off? No they're way worse off without Nightwing and especially without him as their leader, you are only looking at the bad in his time as leader rather than addressing all the good he's done which far outweighs the bad. He led the Justice League several times and very successfully if I may add, he's a better leader than Batman, Superman, and Wonder Woman (said by Batman and Superman themselves, even though Wonder Woman never said it, its implied) who far outweigh Donna's leadership. Give it time and I can tell you, she's gonna make mistakes wayyyyyyyy worse than Nightwing bub.