I have not read all the comments, but there seems to be a concensus that an A and a 121 are both popular, but are also probably on the MM horizon. Surprised I haven't spotted 2600 class railcar, given its versatility for main line, suburban and minor branch use. It also gives scope for modding to a pre-DART push pull. I am not confident enough to try and kit bash a 2600, but would really like this icon of CIE for most of my life. And I mean an original 1950's 2600 of course.