I also think you should start with less than you can fit. Reason being…you WILL want more, so leave room for the next urge!
With breed, I have been hellbent on a few that I was super excited about, only to find they didn’t meet my expectations for what I thought I was getting. My Faverolles would freak and not let me get near her. My Brahma was not friendly. My Leghorns (a notoriously flighty breed), think I am their mother and jump on me for cuddles.

I added them just because I REALLY wanted white eggs, and they are two of my favorites now! My first Barred Rock was my baby and followed me everywhere. I added two more and they can’t be bothered with me.
What I have started doing recently is ordering double of what I want, and selling the extras on Craigslist or Facebook for the cost of what I paid. I also have a family member that orders with me sometimes and lets me pick mine out before giving hers to her. I give myself a week to interact and choose which half I am keeping. I prefer friendly chickens I am able to handle as I REALLY don’t like having to chase a hen that might need treatment or to be checked for something, don’t like when they run away from me like I am attacking them, and I love sitting outside and having a surprise guest sit on my lap. Any flighty/scared chicks are sold/given to my family member. I keep the ones that are the most personable.
Also, broody chickens have been a problem for me, well, one specific broody chicken. She broods every 6-8 weeks without fail, is NOT a good mom, and takes forever to break. I now try to avoid broody breeds for the most part. (My son and husband each pick one breed to add each time we get new chicks, they sometimes pick a breed known to be broody).
I like a mixed flock, in both breeds and feather & egg colors, and rarely have more than one hen of the same breed at the same time. I have avoided Polish for this reason, although I may add a smaller second coop & run in the future for some top hat friends. My single Legbars, Naked Necks, Easter Eggers, and Faverolles have not had a problem for “looking different”. I do have a group of blue/black chickens who are different ages yet have become best friends, so I do think birds of the same color feathers may naturally bond together more.
Everyone has a different experience, so I think it is smart to ask questions and think! Starting smaller gives you room to add more once you know for sure what you like & don’t like. What you think your goal is now may change once you get your feet wet! Good luck and have fun!