Thre are a lot of nice byzantine coins but my best is 40 nummi.It is struck in the Theoupolis Mint, is struck on a planchet measuring 42mm.
I prefer the silver and bronze to the gold solidus which is generically very common and not scarce even in higher grades. I have seen a low number of silver with minimal circulation, centered strikes and good surfaces. The bronze seem to be the scarcest in this quality. I consider these a good numismatic value though don't expect much from them financially.
That is a very nice coin. I am not that familiar with this coinage but I think most of the ancients I have are from this period. I like a medium sized one with two figures next to each other - they kind of look like aliens
I have posted my favorite Byzantine coin before but like the bad follis it keeps coming back. Byzantine Justinian (AD 527-565) AE Follis Obverse: Diademed, draped, and cuirassed bust right / D N IVSTINI-ANVS PP AVG Reverse: Large letter "M", star left, cross top, cross right, Γ under large "M", CON in exergue Bronze, 30mm, 17.98gm Catalog: Sear 158 Struck: AD 527-538 Constantinople I bought this coin because the picture looked like a movie or TV space alien. And not a nice one.