Personally I used sch80, looks better, comes in tons of colors, no words all over it and was only an extra $25 for the entire build.
I know know I could take acetone and stroke the pipes real good to get the words off the pipe and clean it up and then paint it all but the extra $25 was worth not having to do all that myself.
Could be a fun project for those DIYers out there too though.
That being said SCH40 is still great and works just the same especially for the pretty low pressures our tanks see compared to a home/industrial shower/toilet/sink plumbing setup.