You know, I used to think that the cycle of ""looking for things to nerf" was just a meme but now it seems more evident than every that it is completely and utterly true.
She has crazy low mana costs on her abilities, so she can use her spells freely to poke and farm without much worry of running out of mana.
this is false. Clearly you haven't played ori a day in your life since she is notoriously more likely to go oom than most every champ in midlane if she so much as uses anything but Q.
She has crazy damage with thunderlords decree early game. (QWE / QWAuto)
You just described every champ in the game.
She has good range on spells, allowing her to farm and harass from safe distances.
Ori is actually only midrange, and goes oom if she resorts to merely farming with Q and gets zoned out and has her ball reset by the enemy if they catch on to her even attempting to do this.
She has very low cooldowns on her abilities. (She can QWE, and 2 seconds later QWE again, harassing and protecting while still near full mana)
Literally her only low CD ability is he Q, and only once she has put points into the spell. its damage even with AP isn't even high as it is a DPS tool, and is gated by being mana consumptive if used too frequently while also essentially silencing her for its entire travel time on every cast.
QWE for the record costs ori roughly half her mana bar, and claiming she can do it every 2 seconds is simply un-true.
She has on-hit effects of her autos dealing bonus damage, and each auto applies a stack of Clockwork Winding which increases her damage even more.
....soooooo? its not like she itemises for it. Kassadin, Chogath, Diana and even Rumble have similar effects and they all use it better than her too. This is you just listing things she has at this point.
She speedboosts her team with W while slowing down others. (This is fine but again, she's strong enough without it)
you gonna explain why or just make a blank statement?
Cons to Orianna
How about how she lacks any form of hard disable on her basic spells? Literally her only hard CC is her ultimate, which she is forced to use defensively when she gets all in'd. Even Aurelion Sol who is notorious for getting jumped on and being helpless when jumped on has hard CC in his basic spells.
Her AoE outside of her ultimate is very low compared to most every mage as her only potent AoE is her ultimate. her Q and W AoE's are small.
She has less resistances than pretty much every champ in the game to compensate for her E resists, which means she is squishier whenever she isn't holding the ball..which is virtually everytime she is using it offensively or even defensively with an ally.
She is very mana hungry and has no in kit means of getting mana back unlike most midrange mages.
all of her spells have a cast time and or wined up (save her W which gets delayed cast from Q regardless) on top of her Q having a travel wined up, and her being unable to cast spells while the ball travels. this means more than most every mage, orianna has to take positioning and timing/prediction into account as the ball doesn't accomplish anything until it arrives at its location, and cant do anythign else until it arrives at its location.
this is a burden pretty much no other champ in the game has.
Listen, i get it. playing against a good Orianna can feel like you are a cog in her machine, but as someone who despised playing against her once upon a time, I can safely tell you that she is actually not only very balanced (imo she is the epitome of balanced and the most balanced champ in the game), but she has some of the most exploitable weaknesses of any mage.
My advice to you if you have any trouble with her is to do what i did and study up on the champion.
Quite frankly, i feel most people lose to her more out of lack of knowledge and thus don't exploit her windows of vulnerability enough.( which was exactly what my initial problem was back when i struggled against her)
and their newest member 
Keepo
