On how powerful Strange is:
Strange essentially kept his distance, used some - admittedly incredible - defensive magic to redirect Infinity Gauntlet blasts, tried and failed to restrain Thanos, tried one offensive spell that blew up a few rocks and then lost as soon as Thanos got hold of him. The defensive magic was very impressive but defence alone doesn't win fights and at no point did he seem like he had any chance of hurting Thanos.
Iron Man on the other hand, had a serious speed/flight advantage, the durability to actually survive a few of Thanos hits, the skill to keep Thanos off balance in close quarters and he was at least capable of hurting Thanos. Sure, in the fight we saw he only managed to draw a drop of blood but if Thanos hadn't blocked Tony's attacks he at least had a small chance of inflicting more damage.
True but that's mostly because Strange accepted he was beaten as soon as Thanos got hold of him and because Thanos needed Strange alive to give him the time stone. It's not because Thanos couldn't have injured Strange as badly as Tony if he'd wanted to.
The fact Thor had to keep Thanos off balance/go for the kill quickly because he had all 6 stones doesn't diminish the fact he almost killed Thanos with the fully assembled Infinity Gauntlet and that his weapon cut through a beam from the gauntlet to do it.
With a weapon that can one shot Thanos, lightning that can stun/ragdoll him plus a flight advantage, the bifrost to prevent him being sent away by the space stone, the durability to tank power stone/reality stone blasts and the strength/skill to take Thanos on in close quarters Stormbreaker Thor would have a better chance against 4 Stone Thanos than any of the heroes on Titan.
The way I imagine it, Strange could've trapped Thanos in a loop with him and it's possible Thanos wouldn't know how to escape it. Ultimately though, Thanos would either use the infinite time loop to experiment and figure out a way to escape or Thanos pathological obsession would mean he just wouldn't give in and after however many million loops Strange's willpower would break first.
Kaecillius never displayed any offensive magic that would've been effective against Vision either. Neither did the Ancient One.
Like I keep saying, Strange is almost featless when it comes to offensive magic so saying he could take out Vision despite his vibranium body/phasing/speed is a hell of a leap.
Personally I imagine these fights with both characters going for the kill. If you're imagining it as them fighting in character though, then why wouldn't Strange's hippocratic oath apply to Vision?
On how powerful Vision is:
I stand by calling Vision the MVP in the Battle of Sokovia. He did more than anyone to prevent Ultron's consciousness escaping, he ragdolled Ultron with Mjolnir and he used his flight/speed to save Scarlet Witch from the falling city. Most importantly though, we can see in the gif I posted that he fought Ultron Prime one on one and got the better of him. It was Vision's mind stone blast that pinned Ultron down and created the opening for Iron Man and Thor to join in so that together they could melt Ultron's vibranium shell.
On a side note, Hulk ragdolling Ultron Prime once he was pretty much beaten was actually unhelpful since it let him recover, get into the Quinjet and kill Quicksilver.
Vision being ineffective in Civil War had nothing to do with powerful he is, and everything to do with him not wanting to actually hurt Team Cap. There are multiple moments in that film where we can see his power:
- burning the line in the ground as an I could've killed you all just now warning shot to Team Cap
- the reaction speed/durability it took to get in front of the bus about to hit Black Panther and then no sell the hit
- casually knocking Giant Man around
- destroying the airport tower
- accidentally one shotting War Machine
and that kind of power would be effective against Doctor Strange.
The only weaknesses we learned Vision has in Civil War are things Strange isn't able to take advantage of:
- a vulnerability to Scarlet Witch manipulating the mind stone
- a vulnerability to electricity that's pretty much irrelevant unless he has to fight Thor
This isn't really relevant when we're arguing about a one on one Strange vs Vision fight. All the same though, I'd say you're being harsh on Vision. The guy was a huge asset to the team in Age of Ultron and in Civil War he was fighting heroes far less powerful than him, was admirably restrained but made one mistake (it wasn't even that his beam missed, he just didn't factor in where the beam would go if Falcon dodged).