Tall or long for a sorority?

I have a used 25 gallon tall aquarium I bought that needs to be resealed and was just wondering if a 20 long or the 25 tall would be better suited for a 6 female betta sorority? I also plan on having 5 neon tetras,5 glowlight tetras and 5 bloodfin tetras within the tank

So that is 21 fish in total, I would be starting out with 6 tetras before I add the rest just to see how the females react to them or if the tetras try nipping their fins

I'm leaning more towards the 20 gallon long but just want to read everyone's opinions