Lets talk about Garen jungle
So I have been running Garen jungle lately. I am in gold 3 currently. I have done it in the past, and have actually loved it after they changed his E to deal FULL damage to monsters. Let me just say, I love it. His level 1-2 is a little rocky, but once you hit 3 and grab lvl 2 E, it starts going real smooth. The clear time he gets when you build a little damage is CRAZY good. You might think his passive is useless because monsters make it reset, but there are a lot of times in the jungle where you are roaming around, or waiting to go in for a gank, and that extra 50-100 heath here and there REALLY make a big difference, especially when you go and take down scuttler crab and its healing you the entire time.
Now how are the ganks? They are pretty darn good imo. The movespeed boost from Q allows you to almost always get to your target, and the silence is SO GOOD for preventing flashes/escapes. His main asset is the damage tho. You go in for a gank and just annihilate laners with your E.
Are there better choices? well, yea, but does that make him bad? absolutely not... I would give garen jungle a 7-8 out of 10 for overall effectiveness. What do you think?