I’m sorry you lost your flock. That must have been a heartbreaking experience. Before you start over, you must sterilize and deep clean everything you will want to use again. Not everything can be kept though.
@azygous and
@Wyorp Rock might can help clarify how/what to sterilize/clean/get rid of.
I am a big fan of friendly/docile breeds to. I have 7 chickens, and I have found that my top three abortive breeds are the Lavender Orpington (a type of Orpington like the Buff one you are looking at- Look into the different colors before you dive right into Buff!) Speckled Sussex, and Easter Egger (I think that the “Steele Egger” is a Meyer Hatchery thing, so I dont know what their personalities are like and how they relate to Easter Eggers)
I highly recommend the Speckled Sussex. I have one, and she’s sort of like a dog who loves people and never runs away from you. It takes practice and attention of course, but this breed is really very docile and beautiful.
Orpingtons are the same way. While mine still is at that “eww don’t touch me” teenager stage, she’s quite friendly and calm. I would also recommend them. They come in a several different colors besides Buff, such as Lavender, Black, White, etc.
EEs are also the same way. Very outgoing, curious, sweet, and friendly. As the nam “Easter Egger” suggests, they lay colorful eggs. Most commonly Blue Green Or pink, but Tan and white might also become apparent. They one color egg for life, but the tiny might fade through the season.
Mypetchicken has a “friendliest breeds” list. I don’t think it’s completely accurate though since Speckled Sussex are listed as #2 not #1 and that definitely is a mistake
https://www.thehappychickencoop.com/the-top-10-friendliest-chicken-breeds/
In my case, I would chose from your list 3 SSs, 1 EE, 1 Steele Egger or Olive Egger, 2 Orpingtons, and 1 Welsummer. This is entirely my opinion though, so you might have a different approach!