Optimal cell holders

For those that are buying on Alithe cell holders for their packs,
What size/number combination results optimal for you? And cheaper? A shop suggestion?

I initially bought 4x5 holders for building 100p packs (5u inline). But now I realize that those don't "fit my wall" as they are long in excess.
So I thought on doing 6 wide packs. Now I see that there are so many combinations for getting the desired size (3x6+1x2, 3x5+3x6...) and the prices vary so much.

What about the 1x1 types that clip together? Build any shape you like?

I hear from someone that there are some modular holders that are good for making any type of setup but offer a quick way to replace cells (no fusing, just a cell release system). I did not personally find any such holders but I'd be interested in something like that.

As for the exact size it really depends on the objective and target. Sometimes I use holders, sometimes not, depending on need.
After I have a specific final scenario in mind I then get proper holders for that. I was not interested too much in price variations since I don't use holders too often, but only for the more complex projects.