Oof, sorry about the long delay, I have been more busy than anticipated.
Still, I further refined my 1 million diagonal design, with the hopes of creating a 1.5 million one very soon!
The new 1 million triangle was able to beat the I/C wall design offered by CursedPh4nt0m in several test battles.

One aftermath photo. I have also had battles where my ship suffered less damage, but I don't have a screenshot on hand of that. I might do more tests later, however.

EDIT: Accidentally removed the aftermath picture while I was editing this post. Oops. Re-added.
EDIT 2: Also defeated CursedPh4nt0m's Cannon triangle in 2/3 of my test battles:
Aftermath:

and

As you can see, changing up the weaponry made a big difference. Small lasers FTW!
Still thinking on how I'm going to make a 1.5 million design. Not sure if I am gonna make it a small cannon, large cannon, or laser based design. Lasers have the best firing arcs of the three, making it the best choice for concentrated fire (crucial for a triangle design), yet I can't ignore the power of cannons... (and they use waaaay less power, needing power only for the factories in small amounts, leaving the rest for shields and EBs). I also want to include some flak for much better missile defense this time around.