I have used AP exclusively in the past. As mentioned, the pH tests can be difficult to decipher. I eventually bought a Coralife/Hanna ph probe.
I recently purchased the Seachem kits...and then a Hagen GH/KH. I like the Hagen. If I had to choose one over the other, it would be AP.
I say buy it and use the heck out of it. The reactants last about a year or so...then they lost their accuracy in some cases. If you don't like the Hagen kit, then start phasing them out.