Not much of a question in my mind. The Technomage trilogy was the one I enjoyed the most, because the charactors actually "spoke" in the voice of the TV charactors, and so I found it very appealing. Plus, it answered the true, deep questions of the two series that were answered nowhere else. It had a few "clankers" where you realized the author was going against what we saw on the screen, but they weren't vital.
The Centauri series was less well written but still quite good. Vir wasn't particularly believable in some cases, and there was a bit of deus ex machina involved, plus some more serious clankers.
The Psi Corps "trilogy" suffered from the necessary uneven pacing forced by the fact that it wasn't charactor-driven at all. The third book was quite well-done, but neither of the first two seemed to be B5 books in any important ways. You could have removed all the references to the B5 universe without effecting them in any significant way. Not the author's fault, perhaps, but true just the same.