I think the wooden ones are the most versatile, as you can drill and bolt anywhere/anything you want. Thing1's has also had the full sticker treatment about 4 times over... and the flat surfaces are easier for her to do that.
Having said that, most kids don't really get into it until they can use it in the geometry nature intended. (But, it does allow for brainwashing at an earlier age - Thing2 @ 14 mo already can go to 'her bike' when asked).
So... I think whatever is the cheapest you like the look of, really.
Brakes? Meh. They don't need them, nor are they really likely to use them, as they self-arrest speed with their feet. Although... if they are multibike like Thing1 is now, it could be good to teach them what they are. (But... Thing1 is learning that from her pedal bike anyway, which has coaster and handbrakes).
Goldcross has (had?) aluminium Nitro ones for $79 as part of their most recent catalogue.http://www.wooden.net.au
are a local importer that have a broad range, and are in Nth Melb and I believe you can go check them out in person.
Or... just wait for the next Aldi special?