Both are beautiful places. At the end of May you can try them both out, as it's low season. Velero has a lot more on-site facilities and no graveyard, if that bothers you, to overlook, and nicer sea views as well. Some find the cemetery at Magnifico a bother, I find it 'quaint', but not all do of course. Velero has spectacular penthouses of 200 M2.
They both have their attractions and you can't go wrong with either. Both are lux and if you want good, these 2 are just that. I like Velero's management better, but all of this is very subjective of course.
I'm not invested in any way with either of them, BTW.