That's not fanboyism, Pocket Adventure is far superior than Sonic 4.
About Sonic Adventure 2: as I said once to you, I may agree with some of your arguments, but many of them could be applied to SA1:
- SA1 had a complicated and dark story too - both great IMO, in fact, I don't think that storyline is the biggest issue with the next-gen games.
- Being forced to play with other characters is really annoying, but to finish SA1 you had to play with boring characters as well.
- SA1 levels are as linear as SA2 levels. SA2 just feels more linear because sonic moves faster with the new grind and tricks stuff.
I think that everything that's wrong nowadays started with SA1, and the next games just fucked it up even more. But there are many elements of the next-gen gameplay that are fun, that's why I still like SA2. It may not be perfect, but to me is the best 3D Sonic game, SA1 in second (I haven't played anything after Shadow the Hedgehog though).