Choose whatever tickles your fancy, can't go too far wrong with a 7, (westie,robin hood or any of the others). I built a westfield 7years ago
, it was my first kit and it was easy
. Only bit I didn't like was electrics but I never have had a thing for electricity
Apart from that, great car and eminently suitable for a trackday or fast road car. Next door neighbour built a Robin Hood, it was his first as well and he had no problems.
It's down to personal preference really, what style you like and what you want to get out of it.