Over the last few years, as well as "short" ballads with truncated stories (such as Bonny George Campbell, Twa Corbies, Border Widow's Lament etc and a much-shortened version of Sir Patrick Spens), I've sung these which tell a full story. Outlandish Knight, Lord Allenwater, Sheath & Knife, Silkie of Sule Skerrie, Lord Bateman, Banks of Fordie, Captain Carr, Rosie Anderson, King Orfeo, Dowie Dens of Yarrow, Long Lankin, Flower of Northumberland, Robin Hood's Progress to Nottingham and Willie of Winsbury. As noted above, I don't know how many verses I sing in each – I'd have to sing one and count at the same time to find that out!
(I think there are some other festivals that, like Sidmouth, may have ballad sessions. If you're looking for a singable repertoire then such sessions are great because, each day, you get to actually hear how up to a dozen ballads actually work in practice rather than just seeing them written on paper.)