I'm a huge fan of the rules options in Pathfinder Unchained. They do a great job of creating fixes to some of the potential issues with the Pathfinder system without upsetting the entire rule system.

I'm one of those weird people who loved playing my TWF core rogue through all 11 levels of PFS, but I have to admit that the unchained rogue is an improvement. I also actually prefer the unchained summoner to the base summoner; even though the new one may seem less powerful, it's more thematically appropriate. I'm considering playing a summoner for the first time.

I've been using some of the alternate rules systems in my Hell's Rebels campaign, and I like how they are working out. I'm using automatic bonus progression at least in part because I know some of my players like to ignore the Big 6, or spend all their gold on +6 stat items as soon as possible to the exclusion of other items. This way I know their AC is still going up, and they'll end up more balanced. I can now also let them craft---using the much more engaging dynamic item creation rules---without worrying too much about wealth by level.

Some of the rules I wouldn't personally implement. I feel like alignment affirmations will just lead to alignment arguments at the table, and in my experience, multiclassers don't need the boost from partial base attack bonus increases. But I am glad that these options exist for tables that want them.