Live-34 is an excellent experiment in format. The story is told as four half-hour episodes of live radio on Colony 34. The oppressive rule of the authorities is challenged by the legitimate opposition, led by Resident Doctor, the focus of the first episode; the more explosive part of the resistance is led by the Rebel Queen, interviewed in the second episode; and the third episode focusses on an evening in the life of a paramedic called Hex. The soundscape and performances are flawless; I was a little uneasy about exactly why the Doctor and companions have chosen to infiltrate and overthrow this particular regime.
I'm afraid Scaredy Cat didn't leave much impression on me (and I've listened to it twice). It is in keeping with the duller end of the earlier Eighth Doctor audios. Various conceptual entities get incarnated as personalities and the Doctor, Charley and C'rizz eventually clean up the mess.
Singularity brings Five and Turlough to near-future Moscow and an invasion from the far future via an entity called the Somnus Foundation (I wondered if this was a conscious echo of the Putin/Medvedev attitude to civil society). Good soundscapes and acting (with the dismal exception of Mark Bollinger as Pavel), and full marks to the actors who pronounce Королев correctly as "KaraLYOV" rather than "KORolev". Mark Strickson gets some particularly good moments of character development for Turlough. But it went on rather a long time.
I've come to expect total brilliance from Alan Barnes, and in the most recent Big Finish he doesn't disappoint. Brotherhood of the Daleks is the latest in an ongoing storyline where Charley Pollard is travelling with the Sixth Doctor after her time with Eight, from her personal timeline perspective, and trying to keep this secret from Six in order not to damage the Web of Time (a recurring problem for poor Charley). They arrive on what appears to be the planet Spiridon and are apprehended by what appear to be Thals. But almost nothing in this narrative is what it appears to be. The revolutionary Daleks singing "The Red Flag" are a particularly glorious touch. I couldn't recommend this as strongly to newcomers to Big Finish, but those of us who are into the audios in general (and the earlier Eight/Charley arc in particular) will love it.
In summary, Brotherhood of the Daleks is excellent, Live 34 pretty good, Singularity OK and Scaredy Cat meh.