Warriors Orochi 4 and Warriors Orochi 3: Ultimate are massive games, though we recommend Orochi 3: Ultimate. It is rated higher among fans and has more content, despite being the graphically inferior title.
Warriors Orochi has always been a better version of Dynasty Warriors, so if you're looking for an upgrade, it's the easy choice. For those partial to the old characters, you'll be getting a crossover between Dynasty Warriors and Samurai Warriors that will last you a long time. On the plus side, Warriors Orochi 3: Ultimate has 145 characters.