Sargent brand offers a double primed surface, which allows you to use less paint on the painting and to take advantage of the pure white for building up layers and depth. I think it’s a great bang for the buck!
As you get more comfortable with your materials, you may find something that suits you better.
I get a private label brand at my local Omer Des Serres.
nb: I put a sample of a different size as a link to buy some and you can get these in almost any size!