I'll talk about some popular mid lane match ups for Orianna. Remember you might have a different opinion of the match up and that's completely fine, everyone is entitled to their opinions. This is how I've fared against these champions.
- You out trade her extremely hard at early levels. Don't eat a lot of her Q and E's in lane, otherwise the match up will go in her favor. After 6, don't ult at her first if she has her ult up because she can easily just dodge your ultimate and all-in you after. You win this game by just laning against her, don't be too greedy for kills - you will get plenty of kill potential on her as long as you're patient.
- i'll talk about annie because she's seeing much more play lately in solo queue. Orianna destroys annie because of your long range. Everytime she tries to Q you, you can just walk back out of her range and throw a Q+W at her direction and you will get free damage on her. The only thin she can do is an all-in with flash, so watch out for that and you will be fine.
- another easy match up. Try to ward at least one side, and then play extremely aggressive against him. Yes, Karthus has the POTENTIAL to beat orianna if he lands every single skittle, but i've never seen that happen in solo queue. You can shield some of his skittles, and you can literally just zone him out of the wave. The only problem in this match up is the ganks from junglers initiated by a karthus wall, so keep that in mind. It's also really easy to harass the Karthus at his tower trying to farm with ori.
- Playing against lb is probably one of the most annoying things in the game. She has an extremely high burst starting from level 2, so how I like to play this match up is put 2~3 points into e early to shield her burst. She'll probably break the shield, but you shouldn't drop too low as long as you shield the bursts, and then trade back immediately with Q+W+auto. Don't ever be in a position to get chained, and I recommend buying mercury treads + get grail ASAP against her.
- A skill match up. You can definitely beat her early levels by watching her cooldowns, but she becomes pretty annoying with the long range and shields later on. If she ever throws out a binding randomly and misses, you can zone her out until it's back up. Try to outpush her and roam.
- Orianna destroys TF in lane. Watch for his pick a card timings, and play aggressive everytime it's down. This should be an extremely easy match up, as long as you don't get ganked with Tf's gold cards + jungler. I personally like taking teleport against a TF to turn ganks around because Orianna offers way more in skirmishes compared to a TF.
- Zed is a tricky one. You can definitely beat him early game by shielding his damage and just auto attacking him to death, but later on he'll just constantly wave clear and poke at you with his shuriken. Try to get an early armguard, and once you get the hourglass you should be completely fine with this match up.