Personally, I would recommend reading them in this order:
* The Next Generation: Losing the Peace by William Leisner
* Titan: Over A Torrent Sea by Christopher L. Bennet
* A Singular Destiny by Keith R.A. DeCandido
* Voyager: Full Circle by Kirsten Beyer
That's not the publication order at all, but I think it works better that way thematically. It also roughly follows their chronological order (except insofar as Full Circle Part I is set pre-Destiny)
Considering that OaTS comes chronologically last by several months and has little connection to the others, I'm curious why you think it should go second. (And it's Bennett, please. Two of everything but the B.)
Pardon me on the spelling error; it has been corrected.
I'd forgotten that OaTS came several months after the others, but for me, I think it works better thematically if it comes after
Losing the Peace because its themes include renewal and forgiveness.
There's a (very) rough thematic arc to how I arranged that reading order:
Losing the Peace is about the hardships and difficulties that resulted from the invasion, the darkness and despair, and how the Federation begins the process of recovering from that darkness. With
Over A Torrent Sea, we have a very different theme -- hope and renewal and forgiveness, carrying on (simply in terms of emotional content) from the hope that
LtP ended on.
A Singular Destiny, with KRAD's thoughtful but still relatively upbeat protagonist, to me feels like it's about where we're going from here; encountering the next challenge.
Full Circle, to me, closes the thematic arc when it creates that literal sense of new beginnings, looking back on the tragedy and then moving beyond it to embrace the new challenges after we've first encountered them.
It's a very rough arc, and each individual novel goes through the full arc itself in its own ways. But to me, each novel seems to focus (whether intentionally or not) on a different aspect of the process of recovering emotionally from a tragedy, and so I arranged the novels according to that order in the recovery process.