I feel obligated to comment on this list of the all time top 20 tenors from the BBC music mag:

20. Sergey Lemeshev
19. Wolfgang Windgassen
18. Alfredo Kraus
17. Anthony Rolfe Johnson
16. John McCormack
15. Franco Corelli
14. Peter Schreier
13. Juan Diego Florez
12. Carlo Bergonzi
11. Tito Schipa
10. Peter Pears
9. Nicolai Gedda
8. Jon Vickers
7. Beniamino Gigli
6. Lauritz Melchior
5. Jussi Bjoerling
4. Fritz Wunderlich
3. Luciano Pavarotti
2. Enrico Caruso
1. Placido Domingo

I am leaving out number 20 because I never heard of him. He's Russian. That's all I know. The remaining fall into a few well defined categories:

Italians
Enrico Caruso
Luciano Pavarotti
Beniamino Gigli
Carlo Bergonzi
Franco Corelli
Tito Schipa

Swedes pretending to be Italian
Nicolai Gedda
Jussi Bjoerling

These singers represent the Italian tradition, and it's a matter of taste whom you prefer. Tradition would emphasize Caruso. Many consider Franco Corelli the finest Italian tenor who ever lived, and I would definitely move him higher in the list, certainly above Bergonzi. Pavarotti is a brilliant example of the tradition. I have always had a weakness for Bjoerling.

An equally well defined tradition is:

Germans
Fritz Wunderlich
Peter Schreier
Wolfgang Windgassen (I'm counting him as German)

Miscellaneous tenors pretending to be German
Lauritz Melchior (Danish)
Jon Vickers (Canadian)

I think I personally prefer Vickers, but would not wish to slight Melchior. A proper list must include these.

The magazine is British so there are singers in that category that we might otherwise ignore, not being ourselves British:

British
Anthony Rolfe Johnson
Peter Pears
John McCormack (Irish)

I had a teacher who loved John McCormack and made me listen to him. It's not a style that particularly grabs me. I would leave all of these out of my top 20.

That leaves a few Spaniards:

Juan Diego Florez
Placido Domingo
Alfredo Kraus

We should all pause briefly to note that not a single Frenchman appears in the list, unless you count Windgassen. No one pops into memory for preferring French style and repertoire. Or perhaps Alfredo Kraus falls into this category. The Spaniard with the German last name emphasized French repertoire.

Juan Diego Florez, actually from Peru, at 35 is by far the youngest in this list. He is the only representative of his generation and is more or less a one off. The repertoire of the long ago Giovanni Battista Rubini (1794-1854) slips onto his voice like a hand made glove. There are others in his Fach, but no one is so spectacular a coloratura tenor in all of recorded history. Where you place him in the list will depend on how highly you regard the bel canto repertoire.

That leaves Placido Domingo. I see from the comments on La Cieca that many would leave him off entirely. How can this be? I propose that it is the purity of his musicianship and the extreme difficulty of placing him in any of the stylistic categories that creates this problem. He sings a lot of Italian repertoire, but isn't exactly Italian. He has always sung a lot of French opera, but isn't exactly French. Now suddenly in his old age he is a Heldentenor without ever sounding exactly German. He must be in any top 20 list, and even any top 10 list, but where? He is not the best Italian, not the best German, so what is he? I've always said he was the sexiest man ever to walk onto an opera stage. Perhaps he is the best Placido Domingo that ever was.

Here are a few tenors not in the list:

Italian style if not nationality:
Giuseppe di Stefano
Mario del Monaco
Robert Alagna
Francisco Araiza
José Carreras
José Cura
Salvatore Licitra
Chris Merritt
Rolando Villazon

German style if not nationality:
Ben Heppner
James King
Jess Thomas

In his period Mario del Monaco dominated the Italian scene. James King was also excellent. Of the modern guys you can make up your own mind.