In Android: Netrunner, is there a bias towards a particular sub-type of ICE in corp decks?
I'll answer the question of "are particular corporations more inclined to use certain types of ICE".

The answer?  Kind of.  If you look at the whole list of ICE and where the 'good' ones are, you'll get a sense of what each corporation likes to use to stop a runner from getting in.  Just to be sure, each corporation has one of each type of the basic three ICE (Barrier, Code Gate, Sentry).  And, while some of the corporations have different 'affinities' for one type or the other (such as Jinteki and NBN having more code gates then anyone, and Weyland having more Barriers), you'll see more paradigms then straight-out "corporation X uses ICE type Y".

So, as Kit, will you want to use just Decoders?  Absolutely not.  Will you want to take good Decoders?  Absolutely yes.  You should use the best Decoder you can get your hands on as your main Icebreaker, and have copies of the other types for when there are more ICE on the server (consider Omega, if you can get it).