I use a Z1000 brick for my Atlas switch machines and other accessories. It has both 14 volt and 18 volt outputs and I use them both. Probably not ideal, but it is what I ended up with. To be honest I haven't really found the ideal power source for all the auxiliary stuff. The older transformers like the ZW, KW, etc. are very expensive around here and although some of those would probably be good for the aux equipment, I have stayed away from them due to price. A nice, reconditioned ZW is around $225 at my LHS and the others of any size are not a lot less. We have very few train shows and the ones we do have are mostly HO &N gauge stuff, very little O gauge. I have basically stopped going to them.
As to what is best, I really don't know other than what works for you and what your budget will allow.
