I would stick to the PA-44 and PA-34. Their systems are fairly similar. If you study one, you will know 70% of the other. Remember the main difference is the seneca is approved for icing, is turbocharged, and has air conditioning so there are a few more systems to explain. Also the fuel system has some differences as well. Then remember the what would you do questions - if this failed and then that failed and there are no airports, it's a hurricane and complete sandstorm, and one of your passsengers is having a heartattack and you have 15 minutes of fuel left type questions!!:D

I'd say pilotpip and herc driver are right. In my last interview I didnt get questions about my B1900 or king air 200 time. He said "of course you know those planes well, your last airline made sure of it." Tell me about the brakes on the Pa-44. I had to tell him I had no clue, it had been too long since I'd flown one. He didnt like it much and he was pretty rough after that, but it would have been much worse if I had tried to bs the guy.

good question to ask, and the real answer comes down to where your interviewing.....my only interview thus far has been at eagle and all i was asked was to tell him a little about the airplane im currently flying (piper mojave) i think i threw the guy for a loophole because he acted like he didnt know what it was (not suprising) turns out in the end they just really dont ask that much about systems at some places, they just need to fill classes

as everyone else has said, whichever you have the most time ot instructed in (how can you teach about a plane if you don't know it?)

i was asked one systems question in my RAH interview, as both I and the CA in the interview are/were qualifed on the EMB145.