I have Console Wars but haven't had time to read it yet. Does it document how Sega absolutely decimated NEC's TurboGrafx-16 in the U.S. ?
TurboGrafx-16 was the early favorite because of NEC's success with the PC Engine in Japan, Sega failure with the Master System, the lack of MegaDrive software in the first half of 1989, the wealth of PCE games in Japan that could brought over to the U.S., etc.?
Sega's full launch in Sept '89 for $10 less than TG-16, with a recognizable arcade hit Altered Beast and the influx of new software only first seen at Summer CES in Chicago in June, coupled with EGM's positive Genesis coverage in issue #3, #4 and especially #8 (TG-16 vs Genesis) all must have helped along with heavier television coverage.
Edit:
I think NEC's only failed attempt to take a swipe at Sega happened in 1990, either at Winter CES, Summer CES, or both. I remember reading in magazines that NEC had been passing out cards to people trying to explain that even though TG-16's CPU was 8-Bit, it had a higher MIPS (millions of instructions per second) rating than the 68000 in Genesis. And also that TG-16 could display more colors on-screen at once.