We all have our opinions, but I would be v surprised if you did not agree, that at the very least, Smallville has much more suitable actors and characterisation for the 3 main leads they shared with Superman Returns...
Routh's Clark was a pastiche of Reeve's, even if you don't like it, at least Welling has his own take.
Rosenbaum's Lex is a subtley played villan, even making you like him sometimes in the series, almost seeming like the hero he thinks he is.
Spacey's Lex is very one note, just a guy simmering with rage, and then exploding with rage every now and again.(if anyone replies to this post, please do not use that overused image of Spacey saying 'Wrong!', please just don't do that one thing for me)
and last but absolutely not least...Erica Durance's Lois is the best screen Lois to date...smart, tough, cool, attitude to spare, independant, caring, sweet, gorgeous, can kick-ass, and even makes some spelling mistakes and typos now and again like the real Lois should do! She is not flawless after all! lol
whereas whtjamacallher from SR, Kate Bosworth...is just a pure stiff in the role, ok, her acting technically is fine, but she was not suitable for that role at all, she just did not have the right attitude for the role. She was cast by Singer as a favour to Spacey basically, as he had befriended her when she starred in his Deep Blue Sea movie(which she was actually better in, as she suited the role), you can figure this out from the extras on the dvd, you see Spacey talking to Singer about her wanting to see his reaction, 'yeah, she's sweet' etc etc , and then later on the dvd, singer practically pulling his hair out as deep down he knows she is not right for the role, but he feels trapped by circumstance, basically as there was an undercurrent of Spacey only agreeing to shave his head if his pal could get in the movie.