Finished one playthrough of Xillia a few years ago, and Played bits of Symphonia and Graces F. Own Xilla 2 and Zestiria, but haven't played them yet, and I need to get Berseria.
The ones I own are:
Phantasia
Destiny
Eternia
Symphonia
Graces
Hearts
Xillia
Zesteria
Symphonia is alright, it's just that going from Eternia to Symphonia didn't feel like a drastic enough of a change for Symphonia to be hyped up like it is. It just felt like a natural progression and not a big jump in quality.