It's highly set theme-dependent, IMO.
HHRs sound best, from my experience, but you need a clearly rural-inspired set for that.
Diamond Square sound pretty much very good and, being minimal and neutral, aesthetically, can go with lots of themes.
A-molds, apart from being available all the time, are pretty much decent all-around and can hardly be ignored when your theme starts with an A
My votes went to the three above, but I, at least pictorially, very much also like FDLs, H-molds and Cards and Dice (yes) too.
Jockeys should sound very nice too, having two concentric circles (no experience with them), while the Hourglass mold would be inevitable for specific themes, which brings us back to the first line I wrote.
Pitty, for me at least, that there is no Medium Greek Key