I would say:
Dressage foal = Warmblood sire
Hunter/Jumper/Eventing = TB sire
Of course, you could also get a great jumping-type foal from a Warmblood, but I generally associate those with Dressage :)
I personally would skip on the Welsh pony. My gelding Divo is a Welsh cross and stands 14hh, from a 16hh sire. You could risk getting a REALLY small colt.
I would also consider not just breeding the foal and promptly selling it, great prospect or not, especially if it's the mares first. If I was on the market for a hunter prospect, I would choose from a mare with previous offspring so I can see what kind of horse she produces, with what stallion.
'Prospects' tend to be a hard sale. Just because the foal could
be a great jumper, he or she just as easily could not be. You would probably have a much better chance raising the foal, and at least starting it in training. That way people think "Oh look how great it's doing already, I can definitely see myself spending 20k and putting ribbons on my wall" IF
you want to sell it after it's born. If you want to keep the foal, then of course none of that really applies.
Your mare does sound lovely and well trained though. I really like the fact that she's actually BEEN SHOWN and TRAINED and not just "Hurr. I wanna purdy bby horseth" and that you KNOW what kind of foal you want and UNDERSTAND the mares conformation and movement. Obviously color isn't a huge factor here, which is also a super plus, because apparently your mind is on what the horse is going to be able to do...not if it's a slightly darker shade of chestnut, black, bay, or rainbow with purple poka dots.
I would look into both Warmblood and Thoroughbred stallions, my final pick would really rest on the kind of offspring they have produced, their show record, how they would compliment my mare, and of course, their lines.