Ornn is disappointing
I was so hyped for this champion, but no matter how I play him or what I try, I feel useless unless I get 3 kills in a row in lane solo (and that's nothing considering any champion who gets 3 kills in lane will have an inherent advantage). I think I have a pretty good idea why Ornn feels bad to play after playing as him 15 or 20 times. It's how clunky he feels on the whole.
Now normally when a champion feels clunky, it's because of some unintended bug or something that made it onto live and is usually patched out within the same or next patch. In Ornn's case, the problem is that his clunk is a PART of who he is. He's a loner who gets things done, and he doesn't care about how elegantly he gets it done. If he did, he would be raising beautiful stone figurines out of the ground instead of chunks of raw rock. Ornn makes things and breaks things. Grace be damned.
And honestly, I love that about him. As a character concept, Ornn is hands down my favorite champion in the entire game. I love his gruff mumbling and his general grump attitude. He's like an old WW2 Vet that's seen and done it all. Rough, but knowledgeable. I. Love. This. Character.
But here's the deal. It doesn't translate well into gameplay. Every ability in Ornn's kit removes direct control of him for small amounts of time, and by god do those removals of control feel bad. Ornn's biggest issue is that he's way too fair with respect to how people are supposed to deal with him. He has too many weaknesses and not enough strengths. His CC is situational, his damage is easily dodged if you have the slightest mobility, and he generally isn't very tanky early on, making it very easy to just poke him out or outbox him.
So here's what I suggest. Lower Ornn's damage. Buff his CC abilities. Lessen or remove altogether the delay on E, but lower its damage. Increase the knockback CC duration for autoing a brittle target, but lower the max health damage. Shave a little damage off of Bellows Breath, but lower the popup time for Q from 1.125 seconds to .5 or .65. Tanks are taken for CC more than damage these days, the tank update saw to that. Give Ornn a REASON to be picked over other tanks. His kit was designed to have too much emphasis damage and too little emphasis on CC. Just swap the two a bit and I think Ornn will find his niche (and climb out of his 45% winrate slump)