Moving on up!

I currently have a 15 gallon flex. Stock list is as fallows,
10-15 phoenix rasboras
11 emerald eye rasboras
8 corydora habrosus
Numerous cherry shrimp (number unknown)
1 magenta mystery snail.
Live plants,rock,driftwood.
My main reason for wanting a 40 breeder is to give my Fish more room and I want more plants than the 15 gallon can hold as far as surface area.
My corydoras are my pride and joy and they need sand not the shrimp soil they are currently on.
So my questions are what is the best option for filtration? 2 sponge filters, or doing a HOB?
I don’t know that I will be moving the shrimp to the 40 gallon. I would like to add more fish but not sure what to add to the aquarium once cycled and ready for more fish. I would like to keep mainly Rasboras!
Really looking for options and opinions to add later!
Current tank below.
Thank you all in advance.

I would go with the HOB but only if you don’t add the shrimp. It would be more powerful and better to clean the tank I would think and it will help the tank look not so cluttered without the 2 sponge filters. Your tank is beautiful right now can’t wait to see what your 40 gallon looks like when it’s all set up!!