Never even heard of Ellersie and I'm a current student Not heard much about Lyddon either to be honest.
Bod is definitely social, tons of people there so its basically its own little community and its known for having relatively good socials at xmas and stuff. Although bare in mind the distance from city centre social life!
Charles Morris and Dev are also v.social - pretty sure Dev has organised socials (although tbh if the person arranging your halls socials that year is good then anywhere will have alright ones!), and Charles Morris is on campus so easy access to the union too!
Obviously social life is important but I wouldn't choose your accom on the 'most social' one. It's uni halls, 95% of people are going to wanna party So I'd just pick the one you like best if I was you
Having just finished my degree at Leeds, I can tell you hand on heart that there is no halls which is the 'most sociable' or even 'least sociable'. It is completely down to the kind of person you are, and also the people which end up in halls with you. It's a bit of a lottery, but you're bound to find people you like wherever you go. If you want to be sociable, then you will have a sociable experience, simple