5. Rose, Lloyd. The Algebra of Ice
I don't buy many of the PDAs, but Lloyd Rose is possibly my favourite Dr Who author. In this book the Doctor and Ace are investigating anomalies in the time stream (what a surprise, I hear you say) that lead them to a Crop Circle mystery at the end of the last century.
I enjoyed this book, although there was something about the characterisation of Ace that didn't feel right, and that I can't quite put my finger on. On the other hand, the plot is pleasantly predictable in places, which is a bit of a mixed blessing really.
6. Day, Martin. The Sleep of Reason
7. Baxendale, Trevor. Deadstone Memorial
These two are both EDAs. The EDA series is beginning to run down (with the Ecclestone era approaching, *spit*), and with its end will probably come the end of my obsessive collection of new BBC Books (I have all the EDAs excepting The Shadows of Avalon which appears to have gone walkies).
The Sleep of Reason is a good rendition of the "some event 100 years ago has come back to haunt us" genre with the story being told in parallel in third-person "current-day" narrative and first-person diary entries.
Deadstone Memorial, OTOH is fairly standard Baxendale output, although one of the better ones. It's definitely at the "Horror Story" end of the Doctor genre, and doesn't pull its punches (although the punches aren't worryingly strong to start with). It does have both plot and interpersonal dynamic though, which is good. I'm also beginning to like Trix, who is beginning to develop a second dimension to her character.
Despite saying that I'll stop obsessively buying the books, one of the first books to follow the end of the EDA series will be an Eighth Doctor PDA by Lloyd Rose, so of course I'll probably buy that.