The JL of that era were their own worst enemy. Guy was as likely to attack his own teammates as not, Booster and Beetle crowned around way too much, Canary was turned into a bitter feminist stereotype that refused help, Captain Marvels naivety was dialed up to 11, Mr. Miracle did his own thing.. Bottom line, they never really acted as a team, but more as a bunch of stooges clashing vaudeville comedy acts.
While the Titans actually worked together, and had mutual respect, actual strategies, and a leader who could lead.
I take the point about how comically dysfunctional the JLI (the writer stretched and exaggerated the character traits of most of the heroes intentionally, for comedic effect).
Nonetheless, the fact that we can legitimately argue that several of them might, under typical writers, be able to solo the Titans is telling. I think there is just too much power on the JLI, and even with their dysfunction, it's too much.
The fact remains that the most interesting debate here is still which, if any, JLI heroes could solo these Titans. Even with Cap's naivety, putting him down would be a serious problem. The Titans need trickery and special tactics (plus some luck!) to put down Cap, MM, Guy, and probably even the weaker Dr. Fate variant. I know these Titans routinely showed such skill and teamwork (and luck), but there's no way they are the favorites vs. the whole JLI, who still had an in-character Batman.