Hiya!
I'm Fatiha, a second year psychology student and student rep for Cardiff University. To be honest one of the best things here is that there is such a range of accommodation (thought that makes it also difficult to choose haha).
The first 'sociable' accommodation that comes to mind is accommodation in the Talybont complex. If you want somewhere quiet I would choose any Talybont area that isn't Talybont South haha, since students like to hold loud parties there! Although, the Taly area is right next to a train track so you get some noise from there as well. Taly is also favoured because its one of the only university-owned accommodations that has ensuite and is a bit more spacious (in terms of kitchen space I would say). The area is a 30 minute walk away from campus, though.
I would say that if you don't mind sharing bathrooms, then accommodations like Senghennydd Hall/Court, Aberdare (female only accom) and Aberconway are great options as they're right on campus

Some people like to go for private-owned accommodations since they're a bit more luxurious and ensuite is pretty much a guaranteed!
In first year I lived in Taly North and Cartwright Court, let me know if you wanted to hear more about my experiences in those

- Fatiha, Cardiff University Student Rep