I disagree on some of them. Viktor is not really fine, he still sucks hard. There are way too many champs who do the same thing he does (basically waveclear and scale in order to 5v5 later on) but they do it better / they don't suck in lane.
Viktor is super frustrating to play during laning phase, a mage where you have to play fleet footwork to survive the lane ^^.You deal 0, literally 0 damage before the 25/30 minutes, you are basically useless in skirmishes before you complete the hextech and one item.
Ryze is good, but you have to actually play him so much in order to get to a decent level on him, and it's still hard to carry with him cause yeah, he has damage, but he's more an utility mage who roots a champ for 2 seconds and not an hypercarry.
Syndra isn't in a really good spot at the moment, she is "fine" but she isn't strong enough to compete with other mages mid.
Azir is similar to ryze, but he has more potential in late 5v5 fights. He is very hard to learn, he has a decent lane, but he must build nashor tooth which means he will always be out of mana if he wants to push. Being out of mana, or low on mana, in a meta where basically every midlaner buils tear or roa is kinda XD imo. He is very hard to learn like ryze too .
Lissandra is just lissandra. It seems like riot doesn't like her , otherwise I can't explain myself why she isn't getting a buff since she is struggling from a loooong time.
I'd also bring up leblanc, she isn't really bad at the moment in my opinion, she isn't very good too though. But she is going to get the revert soon, we will see out it ends up, even though I'm VERY scared about it. My actual impression on the leblanc revert isn't one of the best I could have. No waveclear in a waveclear meta, and less damage than she used to have. We will see.