3 least sociable extraverts in order
I'd say LSE-Si, ILE-Ne, and ILE-Ti in that order.
ILE-Ti are widely considered the least sociable of all the extraverts, but I disagree that they are because some are quite oriented to people and are fine with making small talk while LSE-Si almost never are. LSE-Si also isolate themselves more in the work environment and don't need camradarie and they don't collaborate with team members when working on a project like ILE-Ti do.
ILE-Ne can't really stay with the same person for long like the ILE-Ti can and ILE-Ne can really be alone for large portions of their lifetimes if they're depressed; they're more prone to debilitating depression than the Ti subtype. Also, the Ti subtype can be a caregiver, can be a teacher, as a psychologist, work in psychwards easily while the Ne subtype can't. And the Ti subtype is more under-stimulated and has greater need for Fe and so they go to parties more like Betas tend to. But i don't know of many ILE-Ne so maybe they are more outgoing than the ILE-Ti, but I know some ILE-Ti who are quite people-oriented and natural in social interaction especially with young children.
Mitt Romney, O.J. Simpson, and Martha Stewart are all LSE-Si and O.J. Simpson was the only one of those three who was anywhere near sociable, but even then not in large groups and even before he was acquitted of murder, he often isolated himself. Deltas tend to scare me really except for some EIIs; Betas are more comforting and more fun, especially Beta STs who are creative function subtypes. Many Gammas can also be comforting and fun but not usually to the level Betas STs who are creative function subtypes are.