I hate to be the bearer of bad news, but I don't think Shyvana is 'the best' or OP. I've been seeing some posts here talking about how op she is, or 'everyone is eating their words' blah blah blah.
But when you look at lolalytics and other sources of data... It's not actually Shyvana that's strong. It's the omni vamp boots. The second you take omnivamp boots away her wr plummets. By the time you reach master+ NOT going omniv vamp sheds an almost 7% off of the winrate, and everything below Emerald can shave up to 3-4% off of your winrate by not selecting the boots. Emerald+ is a difference of 3% by simply not selecting those boots. This is 100% a case of her winrate being artificially inflated because of an item moreso than the balance changes making her 'op'
The funnier part is, even WITH these boots making her 'op' she's still not op, nor the best user of the boots.
The second you filter for Gmaster + Shyvana drops off the face of the Earth to an almost D tier champ whereas champs like Naafiri remain in the top 10.
What these posts have shown is that this subreddit doesn't know how to read data, or take a look at what is going on behind the scenes. What they saw is "OMG SHYVANA GOOD" and then ran around emoting at people... without taking consideration on any external outliers that might be the cause of her spike in performance.
TL;DR
Omnivamp boots are good. Shyvana is still low tier/mid.