got the list that I'd have given you. Cynic is right about bike selection - you can't have a bike that started with double the 47bhp before restriction - so most 600s are out.
The Duke 390 looks like a good 'un to me. You haven't set a budget though - the Ninja 300 (or upcoming R3) are the sort of spiritual successors to CBR400s, GPX250s and the like; and make very good 2nd bikes (as in your second bike, not a winter hack).
Left field option is a DZR400SM - I'd check with the masses on here, but a well liked bike, should be A2 compliant, and will be 'enough' after a 125.
The MT-07 might be worth a look too if you've budget for new*.
*dont forget insurance costs, can give an unexpected amount of zeros on your first bigger-than-125 premium