This question is asked again and again. There is no useful answer. It *might* help if you included your musical tastes and kit you either have or haven't liked before and why, otherwise you'll just get a list of everyone's personal favourite speakers which is fantastic if you have the same taste, but if you do why would you be asking the question? The 'correct' answer is to get out there and listen, but I am well aware this is an ideal and not practical for most folk.
SO saying I'll add some that fit my bill, not everyones; Tannoy HPD do hefty bass and work pretty well with push pull valves, they'll likely finish off your budget though. I actually don't get on with Tannoys but many really do. I do get on with AN-E (or Snell E Mk 1,2, or 3 which are well within budget), although anyone with a taste for loud, brain liquidising electronica is going to pooh pooh their bass fairly enough, but then why would they use valves? If what is most important is the best bass, and I don't read that from your post, then sad to say it is not available for valves at your price point. Avantgarde or some Cessaro horns fit the bill for sound, grunty bass, they're great with toobs, but not so great with your budget...
Edit: I forgot, Living Voice Avatar would be in budget and are a good valve pairing, more of a good all-rounder than a trouser flapping demolition derby type of sound.