I think that is a really important point- regardless of what they make the show about, if Trek ever gets another shot at a series, the first few seasons cannot be shaky or it simply won't last.
That's primarily why I'd favor the Riker/Titan angle.
The writers could build on proven characters that are already familiar to the audience. Now, there would be no way to group together everyone's most favorite 3-5 characters but the chances of having several dud characters (no need to get ugly -- you know who they are
) really plummet.
Throw in a cool new ship and a handful of diverse new characters and it could sustain a large audience.
That would also leave the writing team more time and energy to focus on hammering out a good setting and direction for the show. You're right...there just couldn't be two or three seasons for the show to "find itself." It would need to hit the ground running, and that would be easier to do with a few familiar faces.
obviously its all hypothetical, but the ingredients would be right for a dedicated audience if they made it immediately comfortable and interesting imo