Welcome! Have some fun with this if you want to and spend a little money and do a load calculation yourself so that you may answer your own question about the size of the system.
Above press the button for a rather easy load caculation program.
Then, do what everyone else does. Get a least three written estimates and start comparing. The installation company and their history of happy customers are more important then the name of the equipment they install.
Through this process you will become self educated and have a very good chance of making a good decision and finding an installation company that you trust.
Good luck
"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835