Choosing is up to you. Ask 100 people you'll probably get 100 different answers.
The main things you need is paid quality hosting, there are hundreds of them and I am sure you'll get plenty of recommendations soon enough. You also need at least one paid domain.
Most people use Wordpress to build the site. Think you already know that. While there are theme's specific to amazon affiliate sites, you "don't" have to have one. The theme should be responsive (works well on any device), and have the layout you want. No set in stone layout, it's more a matter of taste.
As for building the site, at the low end you can add the products by hand. Or there are plenty of wordpress plug-ins you can use to build the site and even drip products in the site. Most every one I've seen has been paid, so that is one expense you might incur. Great tool and worth the investment.
You could also buy pre-made or turnkey amazon sites. Which come pre-loaded.
The big thing is to have niche sites. Each site should have a certain category of products. Like dog collars, RC cars, gardening, ect. It's tougher to try and do everything on one site.
You should also research and try to find low competition product lines. You could also target higher priced products, bigger commissions. Better yet find a combination of both. Then your off to the races.
Does this help?
