I prefer infused, because it allows me to boost (tremendously with purple or gold quality) whatever enchants I place on the jewelry piece. I have "mixed and matched" arcane and infused when I felt like my magicka pool was too low, however. But monkeying with armor enchants usually generates a decent pool of stats for my play style. And since most jewelry I use for magicka builds drop as arcane (some are healthy or stamina due to rng), I will usually run with these until I have the transmute crystals to change to the trait I desire.

Now to make things more confusing, (lol!) I do use protective a lot on magicka builds as well, because their physical and spell resistance are too low for my liking with light armor- which also helps boost shield strength since the shield changes were implemented a while back. Finally, I have also used "swift," "harmony" and "bloodthirsty" traits as well. It depends on what I am trying to accomplish. Rarely do I ever use "triune", since armor enchants can help boost my other stats.

On magsorc, arcane is better as pets damage dont scale on SD but on maximum Magicka. On other buids, infused could be as good as arcane, even more considering now every class will slot Entrophy which gives Major Sorcery (not counting parse or trials builds which got it by potion usage).

Spell damage with infused if you want the best dps and don't have sustain issues.

For pvp, if you use shields then arcane, if you slot 0 shields then infused.