Absolutely agree about another Large Logo Blue 37/4. I hesitated a bit too long on this one and regretted it. Another run of these with a different number would be very good and I would not hesitate for a moment this time.
It is also clear from the second-hand prices that they are fetching that another run of Network Rail yellow 37s would also be popular (although not for me personally).
Some more 47 liveries would also be good, e.g. Railfreight Grey, Railfreight Red Stripe, Railfreight Distribution (original triple grey), Trainload Metals/Construction/Petroleum, Civil Engineering 'Dutch', etc. Popular liveries - most of which have been done on the 37 but none on the 47 yet.