I’m a huge Relaunch novelverse fan. These books really kept me going in the absence of new Trek television. I’m still grieving the end of that era of publishing.
(I had never found many of the earlier tie-in books that interesting - the constraints on authors to finish the books with no lasting impact on characters or events made the books feel unimportant.)
The Relaunch Novelverse was something that authors had wanted for a long time. A real way to play in the Trek sandbox and move characters and events forward. Some of the authors seized the most from it, others seem to get stuck in documenting what they saw as history. In either case though, one can seen the influence of the Relaunch writers room thought experiments running through the new shows, to their benefit.
Recommendations? The crossover Destiny, Typhon Pact, and The Fall sequences are all solid overall. Destiny is stands out as great science fiction regardless of its tie-in fiction foundation.
The Bashir-S31/Control, Titan, Voyager Full Circle, and later TNG books are all reliably good to great reads. The DS9 books seemed to start off well and got me into the Relunch books but seemed to bog down. McCormack’s Cardassian books were all excellent. Bennett’s Temporal Investigations are fun reads for knowledgeable fans.
The Relaunch novelverse is not however upbeat and trippy. Its starting point at the end of the Dominion War shapes the backdrop. Even many of the TOS-era books that have a Relaunch basis can be fairly dark, including the much loved Vanguard Series by Mack, Ward and Dilmore.
I definitely have my favourite authors. Most of those became regulars contracted for the new books being released as tie-ins for the Secret Hideout era shows. Simon & Schuster has been managing their room of writers well.
There are however couple of Relaunch authors that I avoid even if it means skipping a key book in a series. There’s one who really knows his Trek stuff but writes exposition-heavy books that ready like background rather than stories. Fortunately, the other authors always fill in what I missed, and Memory Beta is there as a resource too.
In terms of books about the franchise, I have an original copy of the TNG Technical Manual and a few others. I recently got the TAS official guide and it’s great. However, no matter who writes them, I always consider these beta-canon.