I don't have much of an opinion on the other shows, but for Beast Wars, I just can't see any of the show's characters having the charisma and charm to attract the opposite sex(aside from the canon couples).
Rhinox is too much of a computer nerd. Rattrap's too blunt, insensitive, and perverted. Dinobot's too macho, hyperaggressive and even more insensitive than Rattrap. Depth Charge is too violent and mentally unstable, plus he's obsessed with Rampage. I'm not ruling out the possibility of Cheetor entering a relationship when he grows older but for now, his disposition is too youthful and adventurous to get tied down by love. Plus, Cheetor can get a little too overeager and zealous, which may destroy his chances of having a long-lasting relationship. And with Optimus, he cares more about cultivating friendships and exploring unknown planets than entering into a romance.
As for the Predacons, I don't think there's much that can be said about their (in)abilities to attract femme-bots. I can see Tarantulas entering into a "friends with benefits" kind of thing but that's as far as he'd go. Also, there's the chance that he'd eat/maim/torture/disembowel his partner after he's gotten everything he wanted from her.
In short, aside from Silverbolt/Blackarachnia and Tigatron/Airrazor, I don't believe any of the other BW characters are exactly romance material. I'm also of the opinion that romances will only diminish and water down the respective characters of Depth Charge, Rattrap, Rampage, Tarantulas, Rhinox, Optimus, etc. They're much more interesting and better off single.
