Help Me Pick a Tank

[FishNCash]

I just pick up some baby dats to grow. I don't want to spend too much on a new tank. The tank will go on the bottom of my 40b stand. Here are the choices from my LFS. 20R, 20S,29R all sounded good.

Tank
Size

Dimensions
LxWxH (in)

10 S 24x8x12

15 R 24x13x12

15 S 30x10x12

20 R24x13x16

20 S 30x10x14

29 R 30x12x18