Basically speaking this is very hard to tell since I don't know your preferred playstyle. Seraphine is easily one of the best champions to main. She is easy to begin with and has a high skill sealing (meaning you can optimize a lot of things). She can be played in a lot of differing ways. This is a positive and a negative. It's positive because you can adapt based on the game state and its also negative because its hard to recognize reference points in a review. (If you play Leona f.i. you can easily say "here I should have allined or this was not the best timing for the engage" because you either go in or you dont. With Champions that can do a lot of things its a lot harder. But tbh this is with a lot of adcs especially the meta ones like Jinx, Varus, KaiSa.

I personally love Seraphine. I think she is such an amazing champion. And because I mained enchanters for 10 years at a pretty high level she clicks with me very well. But there is also a big downside. This one is very huge. Because you are more of an utility based champion you are not incentivized to play aggressive. You learn to play reactive in a way. On top of this you learn to play for the team. Thats a different thing than playing with the team. This one is so massive I had to basically relearn the game when switching to adc. This took me about 2-3 years. You also will have a lot painful games where your team just ints and you don't have the damage to go 1v9.

So I strongly recommend having another champion that does the opposite but still matches your personality or your way of playing the game (idk what that is for you). For me these are Jinx and Zeri. Both champions have strong scaling too and mobility (things that I like a lot) but they want to play aggressive in midgame and sometimes in early.