I read both. The CFAI material is really interesting and very well written by some very intelligent people. The topics tend to stick better also from reading the CFAI books. However, as hamada mentioned above, it will def take longer to get thru the material
If you really have a passion for finance (I say that because I really feel you get more out of the CFA when you use their material), and you’re afforded the time, I would def try to use the CFAI books in conjunction with Schweser.