I have no problem with the idea
of C/7 -- it's how it was handled that was so frustrating. I mean, it's the final episode of a long-running series, and you just decide to suddenly pair up two characters out of the blue? No, I'm sorry, but that doesn't fly. Had it not been for "Human Error", in which we learn that Seven is at least attracted to Chakotay, it would have been completely unforgivable. As it is now, it's just a bungled mess -- unfortunately, one of many on Voyager
And it's not like they had no opportunity. I think "Human Error" showed that there was potential for the development of a C/7 relationship (regardless of the fact that she was interacting with a holographic Chakotay). I remember even Beltran wondering why they didn't follow up on that and have her start a relationship with the real Chakotay. Then you have "Natural Law", just a few episodes before the finale: Chakotay and Seven are actually stranded on a planet together. Despite it being a terrible cliche, that would have been a pretty good time to get the ball rolling on their romantic relationship, since it's clear by now that the producers were planning to give them one in the finale anyway. But no, there isn't even a mention of Seven's attraction to him, no hint of romance. It's just another boring episode that doesn't have anything memorable or important happen.
I can't really say who would be an ideal candidate for Seven's romantic partner -- I'm not even convinced she really needed one, but I suppose the writers wanted to give her a love interest at the last minute to show us how much she'd "grown", but in typical Voyager
writer-fashion, they didn't think it through. They probably just figured, hey, we're not doing anything interesting with Chakotay, so why not pair her with him? I don't think I would've had a problem with Harry Kim, the Doctor, or yes, Chakotay, if the writers had actually took the time and care to develop a relationship and let it unfold naturally. Unfortunately, that was never one of the writers' strengths, as they proved time and again.