I think they're all limited to 512 models, so in effect, the question is really: which is the most popular / sold out quickest ?
The original intention was that they were specific to the local area, so issues such as demographics etc would come to the fore. However, with all these models being readily available via mail order, it kind of defeats the purpose of having an area reps edition.
For me, for obvious reasons, I was delighted that 47 712 was my local area 47 and I believe has been very popular. The Anglia 47 however seems less so, as will only be of interest to folk who model that area or have an afinity to the actual loco, e.g. if they maybe saw it on a daily basis.