Who are the wealthiest minor houses in Westeros?

I’m not referring to the major families like the Lannisters or Tyrells, but rather the smaller bannermen to these great houses, such as House Hightower or House Manderly. Which are some of the lesser-known, yet affluent houses?

For example, House Celtigar is often overlooked, but it’s said that Stannis considered looting their castle to fund his war, as they are rumored to possess many treasures.