The latter is very popular and getting deployed in several places right now: Honolulu, Thessaloniki, Lima 2, Rome C, …
To nitpick, this is actually Hitachi (the ex-AnsaldoBreda part) and Ansaldo STS (which Hitachi only bought 40% of, and became its own company when Hitachi bought AnsaldoBreda).
Depending on rolling stock and space for equipment, replacing the rolling stock when replacing the signalling equipment might not be required (see, for example, the the London Underground 1995 Stock on the Northern Line).
Is Breda really popular? SFMTA forbade Breda from bidding on this latest round of vehicles because the current ones have been so problematic. I don't think Chicago or Seattle had a much better experience with Breda either.