I haven't tried MySize, but from what I've read it's a good brand!
Personally I've had some RFSU condoms, such as Grande that fits well. Like about the same as Magnum.
I think what one would want to look for a more spacious condom is the nominal width.
A good idea is to buy a sampler pack of bigger sized condoms and find a suitable one from those.
I can believe
@Big Schwanz Acht with his comment about the Trojans.
I know there might be people saying "but condoms stretch so much" and while they do, they might not be comfortable around your penis! Some have a tight ring even though marketed towards bigger guys and so on.
TheyFit and MySize are probably the ones to go for, they're being mentioned anyhow.

Maybe something from Protex or Skyn. Sometimes it's tough to make recommendations related to condoms, as some brands are international and certain brands might be more at certain market place. (I remember the condom shelfs in Japan, so much to choose from. LOL )