There appears a slight GWR bias in the steam locomotives - apart from the industrials of course.
How about 'Heritage Specials' - preserved locomotives still steaming on the rails?
OK, these are reasonably well covered by others.
2 I'd love to see to a high standard are the recently re-introduced / on trials 60532 Blue Peter Peppercorn A2 (Bachmann's looks very decent I admit and goes quite well - mine does anyway) and 71k DoG BR 8P - an average-good model produced by Hornby which can surely be easily bettered.
I stay with my original 'requests' of course:
Parallel Royal Scot.
Jubilee - several guises available.
8F - game for a 'powerful, quality' model.
Class 40.
Ones not done - fascinating to some, relevant perhaps to others, probably not to many.
Bressingham's own 'Thundersley' atlantic tank is a nice one for consideration.
If you stay on the GWR front, then 4-6-0 Halls and Counties are worthy.
Hornby make a good stab at the Castles and Kings, even if they're a little over-geared!
Al.