Honestly, it doesn’t matter which shape your base takes, as long as there is an entrance which has a U-shaped bend in it. If it does, then you should be able to defend it well. Of course there should only be one entrance, but once it’s taken shape the hard part can be upgrading the walls.
Over the weekend, I finally researched Depleted Uranium 4 armor. This allows me to finally upgrade my walls. Since I was going to be away for the weekend, I also left my fleets both defending and farming Zynthium. As it happens, my base wasn’t attacked, but even though I had a lot of Zynth saved up, I knew I was still going to run out before I could finish upgrading my walls. This is where a plan is needed and knowledge to know where to upgrade first.
First and foremost, the walls facing an incoming fleet should be upgraded. After you upgrade your outside facing area, you will want to strengthen the walls between your turrets. Then last we want to finish up with the walls behind, to minimize splash damage.
I went ahead and took a screenshot and then highlighted which areas to do First, Second, and Last…
You’ll notice on my base I actually have a Two U-shaped bends. The only person to get through this design actually never came in for a second attack, since they did so much damage to the other nearby mines and buildings, that it bubbled me for about 2 days. He did however manage to lose 3 strong fleets getting in, and ended up leaving with about 10-15% of my resources. A good trade I would say.