While Magnetos uni is definitely an improvement over the base kit, it’s not a huge improvement. Aesthetically, however, it’s one of the best looking unis in the game imo. I bought the uni because Magneto is one of my favorites in the comics and this is probably my favorite look for him.
It's super helpful. I haven't tried it on GBR yet. But on ABX, it's super awesome.
Back when I don't have his uni, I would need to hover around to avoid the Frostbeast's attack making it tough to score high. With the uni, you just need to stand there doing his rotation and you won't get damaged. Easy 200k if you have him at T2 only and not so descent build.
All of your other options are better than Magneto imo. Magneto is already a good character and uniform doesn't provide much.
Hulkbuster and Rocket uniforms make the characters better overall. Only downside is Rocket loses heal.
Wasp's uni makes her an i-frame machine but she still has super low damage. Uniform's team passive is pretty good tho. I'd buy it if you play TL manually, otherwise skip it.