Planted Tank Guru
Join Date: Sep 2004
Location: Garden City, KS
Just to play devil's advocate here...
To some people, bigger is not always better. I've had large tanks in the past, at least in my SW days, and I eventually decided that smaller tanks are easier to work with, and lower-cost/quicker payoff as well.
Yes, tiny nano tanks present a few issues, but generally speaking, anything 10g and larger is relatively practical. You have to remember that the larger the tank is, the more plants will be required to "complete" the scape. This means that both money and plant selection must be available to you. When you don't fully stock your tank with the correct amount of plants, algae and other issues can present themselves that wouldn't normally do so with a packed tank.
Then don't forget that finding and arranging hardscape materials is more of an undertaking the larger the tank is. It can be frustrating to look at your tank and feel like there is just too much open space, or negative space. These are all things that should be considered, IMO.
With a smaller tank, say, a 20-long (just, one of my favorites), you can probably "complete" your scape and be satisfied with the way it looks upon the first, immediate planting. And I've never had a problem (in the FW world anyway) with a small tank crashing so fast that by the time I got home from work it was too late. I'm talking about 5 or 10 gallons here, not 1g pico tanks. Yes, the smaller the tank is the faster it can fall apart if something is wrong, but it's not lightning fast or anything. Not for your typical, planted community-esque type of tank. Maybe if you had a specialty tank, with specific parameters, like a Sulawesi biotope, or a brackish tank, that would be different.
So, I'm not a fan of the "bigger is always better" mentality. I do love big tanks, though, don't get me wrong. Just, bigger does not necessarily equal better.
(And yes there have been stories of people wishing they had gotten smaller tanks after the fact. It has happened to me before, and I've read stories on this very website).
With all of that being said, I will echo the others who recommend a 40-breeder. Those are just the perfect size, IMO, to create a beautiful 3-dimensional aquascape.