I own a Beseler 67C that I bought new in the late 1970s. It served me well for decades. About 5 years ago I bought a dichro head for it, and used it for about 3 years.
About 2 years ago I bought a used Omega D6 with an Ilford Multigrade 400 head and controller (plus lots of lenses, carriers and other accessories). It is what I'm using now, but I'm not getting rid of my Beseler 67C.
I've worked with other Beseler enlargers (23C series and 45 series) and other Omega enlargers (D2 and B22) and would say, in general, that for the North American market almost all the enlargers made by either company would be a good choice, if they are in good shape. In some cases, accessories are more widely available for some models as compared to others, but that problem is rare when it comes to Beseler or Omega.
Many will recommend that you start out with a 4x5 enlarger, due to the fact that they are very robust, and they are both relatively plentiful and relatively cheap on the used market. If you have the space, and find a good, well equipped one, they can be a great deal. I think though that it would be a mistake to wait for months or years for the perfect deal, if good examples of something as robust as a Beseler 23C-II or Beseler 67C are at hand, with accessories, and if you aren't planning to shoot formats larger than they handle.
EDIT: 2 other points:
1) there are other great enlargers around. Durst, Devere, Meopta are examples. It is just that the availability of these enlargers and their accessories is better in Europe than in North America. If you were in Europe, I'd be cautioning you about the availability of Beseler and Omega equipment;
2) my only complaint about the Beseler 67 series enlargers is that the largest size they work with is 6x7. The Beseler 23C series works with sizes p to 6x9, so if you like old folders or ...