Ooh goodness, Big Finish is my absolute favourite. It's why I'm madly in love with Eight and Omega. A piece of advice? Don't listen to an audio with Daleks while on a treadmill. I got glared at by the trainer on duty when I suddenly squeaked and nearly went off the end at the unexpected YOU WILL BE EXTERMINATED.

ETA: The folks who do the audio dramas for the Black Library are also stellar.