Alva has a sweet tone, effortless agility and actually separates the notes in the 'runs' (rapid scales) - although sometimes as the cost of aspirating a little between them. He also has an 'ardent' quality that suits the role of the Count (in disguise), and he does a decent acting job - although nowhere near as good as those true masters of this difficult art: Berganza and Prey:
However, getting back to Ecco Ridente - I have come across this performance by Richard Conrad:
Like Alva - Conrad also has a lovely, sweet flexible voice. Conrad's performance lacks 'drama' and he does not fully separate the notes in the run - however; his use of trills as decorations (a trill is the rapid alternation between two notes) is astonishingly good.
Indeed, I have never heard any tenor who comes near to Conrad in his control of the trill: it is extremely rare for any singer to be able to do it, and much rarer in men than women (at least, with modern vocal production techniques - the fact that trills were written for men in the Bel Canto era suggests that the ability was commoner in the past).
In fact the only other really convincing trill I have heard from a male singer was John McCormack in this Handel aria:
Unsurprisingly, McCormack and Conrad have the same basic type of voice - similar strengths and limitations; and I think this is the case for all singers, and indeed all people - are strengths are the other side of the coin of constraints: and this is why it is good to have many singers (and people...)!
There is no perfection in singing - not least because the single most important aspect of singing is tone; which is natural infinitely subtle and unfakeable; becuase it is expressive of the person, of the inner self. All great voices are expressive of distinctive personalities.
At the bottom line, we want singers of beautiful and affecting tone - we want to be moved by singing: and other technical aspects must be fitted-in around tone as best as maybe.