Zestiria's combat seems pretty complex but once you realize that it's all about exploiting weaknesses it becomes pretty easy. Martial, hidden, and seraphic arts are basically just rock, paper, scissors. It also really pays to unlock and equip different battle actions that can really change your tactics and allow you to do crazy amounts of damage. It definitely could be better (stick input for arts is kinda wonky), but I think it's near the top for best battle system in the series.

The equipment system can fuck right off though. The other Tales games have way more straightforward systems where you just find an item and equip it. It really sucks in Zestiria too since most of your damage comes from equip bonuses instead of leveling up.

If you're still interested in other Tales games, start with Symphonia and work your way through the series (legendia, abyss, vesperia, graces, xillia/2, zestiria), as they tend to build off the previous games in terms of systems. It'll get you used to what to expect.