I usually seine my own suckers so they are FREE! I can keep them alive easily in an aqualife bucket from frabill . 6 gallons of water and 1 chunk of ice will keep 2 doz alive for 12-14 hour no problem.
If bullheads are better why have all my fish over 30lbs been taken on suckers. Bullheads are cheap ok but flatheads are not attracted to them as well. Even in 80 degree water a sucker will live and kick for hours if hooked correctly.
Bullheads are popular because of their abundance not their superiority.