A 'positive kind of "envy" without the sense of resentment' is, of course, envy.
While the OED (for envy, noun) comes out punching with definition 3a
The feeling of mortification and ill-will occasioned by the contemplation of superior advantages possessed by another
it gives Definition 4 a header stating Without notion of malevolence, and 4b as
b. A longing for the advantages enjoyed by another person
and an example:
1891 Your success excites my envy.
Note, this is a "positive kind of envy". Or at least "neutral".
As for envy (verb): after dispensing the negative definition the OED says
Also in less unfavourable sense: To wish oneself on a level with (another) in happiness or in the possession of something desirable; to wish oneself possessed of (something which another has).
Neither definition has been updated since the 19th century, so the OED is a bit behind the times. But the noun and verb can be used without a trace of 'negativity' (eg, malevolence). This doesn't mean envy is no longer among the cardinal sins: what matters is whether that envy includes the desire of stripping the envied object away from the person so that you can have it instead. (Similarly, pride is the number one cardinal sin, but that is only in the technical, biblical sense (man exalting himself to the place of deity)), it doesn't include things such as pride in one's achievements.
Both 'A longing for the advantages enjoyed by another person' and
'To wish oneself on a level with (another) in happiness' are hardly malevolent.