Sorry I'm late to the Republican party. (See what I did there?) At any rate, I wanted to wait until I could spend some time with this list. And what a list! It's hard to pick a favorite, so let me just comment that something about that sacrificing scene reminded me of this image of Dido sacrificing, from the Vatican Vergil, ca. 400 AD. I guess these iconographies are pretty stable.
Thank you. That's a fascinating image. And, speaking of this particular stable (pun intended?) iconography, I think we need a sacrificial scene with a lighted altar involving a goat, in addition to the one with a heifer, in order to properly match it. (Pun intended.) Here's one I like, even though it didn't make my top 10 for this year: Roman Republic, L. Pomponius Molo, AR Denarius, 97 BCE. Obv. Laureate head of Apollo right, L•POMPON• MOLO / Rev. Numa Pompilius [legendary second king of Rome after Romulus], holding lituus in left hand, standing right before a lighted altar, at which he is about to sacrifice a goat, which is led by a victimarius standing left, NVMA•POMPIL in exergue (MA and MP in monogram). Crawford 334/1, RSC I Pomponia 6 (ill.), BMCRR Italy 733, Sydenham 607, Sear RCV I 214 (ill.). 19.7 mm., 3,86 g. *[Double die match to CNG E-Auction 157, Jan. 2007, Lot 149?] *See RSC I at p. 77: “This type is an allusion to the supposed descent of the gens [Pomponia] from Pompo, one of the sons of Numa Pompilius, who is here represented as sacrificing to Apollo.” Crawford’s interpretation is the same; see Crawford Vol. I at p. 333.