The new millennium has clearly heralded a new world order in Godzilla fandom. A Top 10 list with only three Ifukube titles would have been unimaginable 25 years ago, but today there is a larger (and more diverse) pool of composers to choose from.
Nevertheless, the #1 entry is the last one I would have expected. To my ears, Koroku's music for THE RETURN OF GODZILLA has always sounded like a third-rate knockoff of John Williams' SUPERMAN score, and comes off as more coldly heroic than terrifying.
I'd go with Ifukube's original as #1 for obvious reasons. Godzilla Returns is in my top 10 but not 1 for sure.
I do like Sato's Minus one a lot. It's probably in my Top 5 Godzilla scores but falls outside general kaiju top 10 since I love Rodan, DaiMajin, Gargantuas, even Yokai Spook Warfare (tho, is that really kaiju?).
I'm the rare fan who only enjoys a few of the Ifukube scores for the GODZILLA series (such as Godzilla vs Destroyah from 1995). My favorites are spread among the other composers, and especially the Millennium era (big fan of Michiru Oshima!). My own top 5 would be:
1. Godzilla vs Megaguiras (2000) 2. Godzilla Against Mechagodzilla (2002) 3. Tokyo SOS (2003) 4. Godzilla vs Biollante (1989) 5. Godzilla vs Megalon (1973)