FFXIII is better definitely. Yet i wont consider it totally an RPG (if we are talking about the main story), which is why most people hated it. FFXIII-2 was way more an RPG, still after completing the game there is almost no challenge for you other than doing the story again (witch FFXIII is more of an RPG in postgame). Still 13 gave me 95 hours, 13-2 gave me 60...
Yet the story of XIII is one of the better I have seen. I consider the story telling a good thing. Nowadays we are used to get the story shouted with details out and dont even think about it. The datalog is just for people who had a bad time figuring it out. XIII-2 dosent have anything to do with the first part and therefore the story is wrong. Seeing it separetly is another thing, a good story, yet not as good as XIII.
The character development is awesome. It puts you with more realistic characters, getting scared, going all talk to hide their fear, becoming distant, etc. People may consider Lighting a stereotype, but she is very different from the common cold person, taking more initiative towards others, if the dont cooperate its their problem. And so is the others witch i wont tall now... In XIII-2 the only character development you get is Sehra changing her 5 year old attitude for a woman after calling out Lightning's help first and learning how to use a sword and be sure of herself in half second.
And for tha gamplay... It needed the change. People say it plays by itself, not realizing the main part of battles is to create and use effectively paradigms. Also the fact of using Auto Battle is obvious it will play on its own. If you play a game on easy how will you complain the difficulty is too easy? Yet XIII-2 alowed you to use Ferral Links and change leaders during battle. For the sacrifice of techniques such as Summon, good things in good things out.
Finaly the equipment and items. I dont see a dam difference in a stupid floating computer and a more ridiculous bird-girl. But the floating computer alowed you to upgrade equipment. Witch weapon and accessory to chose and upgrade was fun and complicated on XIII. In XIII-2 getting the final weapon is rather easy you dont have to put any effort into getting it stronger other than collecting fragments. And eaven more you equip almost no accessory.
Most of above is a personal opinion and NOT A FACT. yes i liked ff13 way more than 13-2 and no that dosent mean its better.
13-2 fixed some issues with 13, but for every fix, it took a few steps backwards putting back on equal footing.
looking past their razzle dazzle exteriors, these are examples of some of the worst excersizes in game design i have ever seen. it really is embarassing to see so much money wasted on such expensive projects.