In the case of Madonna's singles, M. herself draws a fairly bright line between her first- and second-tier material: True Blue gets omitted from greatest hits/best ofs, etc., as does Angel (which M. apparently hasn't performed live since the Like A Virgin tour). Other second-tier M. singles (from her first 'imperial period' as it were) include Spotlight and Causing a Commotion.
While some of the affection that fans tend to feel for these tracks stems simply from the fact that they haven’t been overplayed the way beloved signature songs undoubtedly have, these tracks are also just good, unpretentious, uncluttered, dance-pop records - they're almost garage dance-pop. Unlike Borderline, Holiday, Like Virgin, Material Girl, Crazy for You, Live to Tell, etc., they’re not massively better than their non-M. competition at the time. They almost certainly wouldn't have made M. a mega-star, maybe no kind of star. But they're a lot of fun, and the simple/more human-scale M. that they project has a special place in fans' hearts. Or so it seems to me!
The third single from Madonna's Like a Virgin album, Angel didn't get a proper video, but the 'promo-only' vid. that Warners UK spliced together from previous outings is enormously fun:
What an intoxicating visual presence M. was in her first bloom of stardom, and what a debt M. owes to Mary Lambert, the director of the vids. for Borderline, Like A Virgin, and Material Girl. M. is very sexy in all of her early videos, including Lambert's three, but Lambert also (i) always gets M. to act, and (ii) connects M. with wider traditions of cinema representation of women (both Hollywood and indie/European art-house). The upshot is that Lambert's videos for M. are sexy, but they're also analytic and layering. Seeing them pulled apart from their original soundtracks and cut against other effective but comparatively one-dimensional video sequences is incredibly telling: Lambert's images lift everything around them. Madonna Studies starts here.
Soundtracked by arguably the paradigmatic, second-tier M. tune, Lambert's achievement is especially impressive: the 'promo-only' video for a second-tier single distils something like the essence of M's early style and appeal.