I personally went from HO to N about ten years ago and I have never looked back. Due to space constraints, N Scale has been the best solution. One of the main reasons I switched to N Scale was being able to get the long straightaway runs that are infeasable to model in other scales. Modeling an obscure area on the old EL Main has proven to be more of a challenge - not because of the scale - but because of the availability of research material. But I digress... If I absolutely had to do it over again (like in the event that N Scale did not exist) - I would probably go with Z Scale for the same reason I went from HO to N. Joseph
Even though I am in N I am tempted to say HO. The reason I don't is that I love long trains (which unfortunately I won't be able to run on my layout in N) and thus would probably opt for N because of longer unit trains. I am also convinced that N might be the scale in the future if engines get larger as the SD90's have. If everything was the size of the SD90's then I would love N scale. The SD90's are almost TT size. I now have my updated answer. TT would be a great size, but the offerings are just too limited. Many, including myself, think TT would have been the perfect compromise between small and visibility. If TT had the same selection as N scale, I would definitely be a TT man.
I am starting all over again.. Got back into Model Rairoading 1 year ago after being away for 20 years. Thought about the other scales for a few seconds.
If I started over again, I would probably stick with N-scale. I am starting over again after 17 years away! John