I built my 3 vessel system all based on The Electric Brewery. I ordered a pre-assembled panel from The Electric Brewery and then assembled my own kettles from Northern Brewer's 20 gallon kettles. I had a welder weld in couplers and tri-clamps for the electric elements. I really like the control panel as it's all constructed from readily available parts and I don't believe I'll ever be beholden to some proprietary technology and code. If my house burned down tomorrow, I would rebuild my brewery around this control panel. Pretty short learning curve as I was already brewing on a 3 vessel system. It's not set it and forget it, but I'm one who enjoys being part of the brewing process. Not right, nor wrong, just me.
For kettles, I would look to Spike, SS Brewtech, etc. to have something that was ready right out of the box for the HLT, Mash Tun and Boil Kettle. I like the idea of SS Brewtech's mash tun, but I still have concerns about the flow through the mash tun when continuous recirculating the mash. I probably would lean towards Spike based on what I've read and watched online. With what's available today, there's really not a reason to build out the three vessels from scratch like I did unless you just enjoy the tinkering aspect as I found it tedious.
Wherever you plan to brew, I think it's equally important to think through the process. There are layout issues I wish I could change today, but I was restricted by the basement layout and where plumbing previously existed.
Happy to answer any other questions.