They're all very popular picks it seems at the minute, usually see 1 of them in most games.
Jinx - never really understood the whine about her. She has no escapes so pick a hard engae support like Leona/Annie etc and just crush her in lane. Definitely not ban worthy.
Shyvana - Horrible lane bully who can just abuse top lane all day by building tank with maybe a BOTRK and crushing faces. I do LOVE playing her though, so much fun to just press W and run at fools.
LeBlanc - So deadly when in the hands of someone with good mechanical skills. Once she gets a kill or 2 it can snowball horribly and there's no coming back once she can just pop team mates in a combo. I always ban her as it's either the enemy team rolling us over with her, or my own team failing horribly with her...
Was just about to replying with something similar,
The best way I've found to deal with a Jinx is just to pressure hard from the beginning, I usually play support Thresh/Leona/Nami and just focus from the the start.
Tank Supports with Dorans Shield at lvl 1, just harass and make them loose cs usually hit lvl 2 in most games before they do and then just fight force a back.
The problem most people have in lane against jinx is if you get low mana/health and need to back you can almost be certain your tower is lost, she can melt towers something shocking