I can play every role decently well, so instead of a jungle mains opinion you'll get a jack of all trades opinion from me :D
The junglers I usually play are Elise, Shyvana and Sion.
Elise for obvious reasons, if I fall behind and can't come back easily I can just max E, build full tank with 40% CDR and just be a stun bot for my team, it's a great fallback pattern since it works just so well if you can reliably land your stun on people. Cons? skillshot reliant?
Shyvana I use just to clear fast, easy counter jungling, all you need is a stalkers blade with devourer enchant for damage since you clear so fast you'll spike your damage extremely early, then you can just build full tank and become the raid boss you were always meant to be, sometimes picking up either a wits end for more on hit damage or a last whisper if you intend to annoy the enemy tanks too. Cons are she's sadly very easy to kite and early ganks can be hard if your laners don't have CC and your chilling smite is on CD.
Sion because he's just fun, his ult is so satisfying to use to engage a fight (or miss it, it's either fun or funny depending). Cons would be how his ult and Q stop working sometimes, defective zombies man, not cool.