Selina definitely. The rest are either designed with a clear ending in mind (Silver, Andrea, Sasha) or are terrible/boring.

For Dick, Babs is my preference. I'm a 90s kid and I liked them a lot in the cartoons. To the point that coming into the comics later and finding out that they are NOT the same age and never dated as Robin and Batgirl seemed strange to me. I do like Kory a lot too though, so she's my second favorite option for him.