I'm currently writing up a paper where del Pezzo surfaces play a prominent role (at least, some noncommutative version of it). And my co-author likes to write Del Pezzo surface. It turns out that Miles Reid also has an opinion about it, for which I quote him from his paper Nonnormal del Pezzo surfaces:

0.7 The great debate Rendiconti del circolo matematico di Palermo 1 (1887), p. 382 records the admission to the circle of dottore Pasquale del Pezzo, marchese di Campodisola. It would be interesting to know why Corrado Segre writing in the same volume (p. 218, 220, 221), along with every subsequent Italian writer, spells the Marquis' name incorrectly with a capital D.

So that settles the debate then.

Another piece of colourful language from the same paper (it is Miles Reid after all) is the reference in §2.10 to an SGA2 exposé and Hartshorne's local cohomology lecture notes (both after notes by Grothendieck) as Holy Scriptures.

Luckily said co-author told me he has no strong preference either way.