Same as everyone said but I will add don't get the great value brand. they are really thin and flimsy. I had one full of water and it crushed in my hand just trying to pick it up. They also tip easily. use the actual SOLO brand ones.
I'd put the small square pots a notch above solo cups as they are square, Less prone to tipping and utilize space better in the beginning because they can go side by side nicely where solo cups leave lots of open space between cups.
Also if you have something like this, it makes it to where you can pick them all up and move them with zero risk of them moving around. ( I wish I had these)
Only thing clear cups are good for is if you double stack them on a normal solo cup for bottom watering. that way you can see how much water is in there.