Merry Christmas to everybody! Massive wall of text incoming.
So I've been getting into some Neo Geo gaming lately (emulation, I'm not that rich yet to afford an AES or MVS, someday I'll have one though). Looking at the games, the system has some of the best arcade style games in almost every genre, being an arcade system primarily obviously. Getting into the tech specs when compared to the Genesis here's what we got:
Neo Geo AES (same as the MVS):
Main processor: Motorola 68000, often produced by another manufacturer, running at 12 MHz
Co-processor: Zilog Z80 running at 4 MHz. This is also used as an audio controller.
Main memory (used directly by 68000): 64 KB
Main video memory : 84 KB
Video memory: 64 KB (32 KB x2)
Palette memory : 16 KB (8 KB x 2)
Fast video RAM : 4 KB (2 KB x 2)
Sound memory (used directly by Z80): 2 KB
Display resolution: 320×224 (many games only used the centermost 304 pixels)
Color palette: 65,536 (16-bit) (Not RGB565, but RGB666, where the lowest bit of each channel is shared with one bit)
Maximum colors on screen: 4,096 (12-bit)
Maximum sprites on screen: 381
Minimum sprite size: 1×2
Maximum sprite size: 16×512
Maximum sprites per scanline: 96
Background layers: 0
Aspect ratio: 4:3
A/V output: RF, composite video, RGB (with separate 21 pin RGB cable FCG-9).
Sound chip: Yamaha YM2610
4 FM channels, 4 operators per channel
3 SSG channels
1 Noise channel
7 ADPCM channels
Work RAM (sound): 2KB
Sound ROM 128KB on-board (only less than 32KB used)
up to 512KB sound ROM on cartridges
Processor: Motorola 68000 16/32-bit processor @ 7.67 MHz (MC68HC000, CMOS version)
Co-processor: Zilog Z80 8-bit @ 3.58 MHz
Video display processor: Yamaha YM7101, derivative of the VDP from the Sega Master System
Memory: 64K work RAM (68000), 64K video RAM, 8K work RAM (Z80). Later hardware had an internal 1Kx16 ROM for the license display screen.
Display palette: 512 colors (3:3:3 RGB)
Onscreen colors: 64 (normal) or 183 (shadow/highlight mode)
Maximum onscreen sprites: 80 (320-pixel wide display) or 64 (256-pixel wide display)
Resolution: 256×224, 256×448, 320×224, 320×448, (PAL and NTSC), 256×240, 320×240, 256×480, 320×480 (PAL only), 256×192 (SMS games only)
Sound: Yamaha YM2612 5 channel FM and 1 channel FM/PCM, Texas Instruments SN76489 4 channel PSG (Programmable Sound Generator)
The Neo Geo had an edge on some aspects, including more memory, a better sound chip, a wider color palette, a more powerful video processor, allowing more sprites at the same time and a slightly faster processor (the same 68000 that the Genesis had, and many more game systems and computers from the era used).
Resolution-wise, they were both capped at 320 x 224, even if the Genesis had PAL mode capping at 320 x 480, most games of the time used 320 x 224 or 320 x 240.
The Neo Geo also had the advantage of having larger capacity carts, with the use of bank switching they got this capacity almost to 900 megabits. I'm not sure if the Genesis could technically support such capacities on its carts, cost issues aside.
Now on to the 32X. At least on paper it sounds as much (if not more) powerful as the Neo Geo:
Processor: Two SH2 32-bit RISC processors with a clock speed of 23.011 MHz, approx 20 MIPS each
Video RAM: Two linear framebuffers with support for RLE compression and an overdraw mode to simplify compositing objects with transparency. All scaling, rotation, and 3D operations are performed in software on the SH2 processors.
ROM (BIOS): 3 kb
Color depth: 32,768 simultaneous colors on screen at standard Mega Drive/Genesis resolution. Video output can overlay Mega Drive/Genesis graphics or vice versa. Mega Drive/Genesis video effects such as shadow or highlight do not affect 32X video.
Memory: 256 kB (2 MBit) program RAM and two 128 kB (1 MBit) framebuffers.
Audio: Stereo 10-bit PWM (Pulse Width Modulation) mixing with Mega Drive/Genesis sound for a total of 12 audio channels of varying capability, 20 with the addition of a Mega-CD/Sega CD.
I/O: Same as Mega Drive/Genesis.
Storage: 32X cartridges are fundamentally the same as Mega Drive/Genesis cartridges with some small differences in the plastic casing. A few CD-ROM games were developed that also required a Mega-CD/Sega CD.
Compatibility: Compatible with Mega Drive/Genesis models 1 and 2, JVC Wondermega/X'Eye and the Multi-Mega/CDX. The 32X does not work with the Genesis 3 which lacks some of the necessary interface logic.
The processor speed is on par with the Neo Geo, 32X having 2 processors at 23mhz and the Neo Geo having one at 12mhz, and a Z80 at 4mhz. Due to the different architectures, I'm not sure how they compare to each other and if the speed would make a big difference. The color capabilities of the 32X shit all over the Neo Geo, having a max of 32,768 colors compared to the Neo Geo's 4,096. Sound wise they may have a tie, due to the awesome Neo Geo sound chip being better than the Genesis', but the combination of Genesis + 32X + Sega CD gave it 20 channels of sound + the capability of having CD music streamed from the Sega CD. This may give the 32X (with the Sega CD) the upper hand by an infinite margin, due to the possibilities of having any kind of music available, without limits.
The 32X could even do some decent 3D with textures on software (?) as seen in this review of Metal Head, something the Neo Geo could not. It's pretty understandable, due to the fact that when the 32X released, the Neo Geo was already 4 year old hardware, but VERY powerful and impressive even then in 1994.
Getting to the bottom line: Could we have had perfect ports of Neo Geo games on the 32X if developers were interested? Is the 32X comparable, inferior or superior to the Neo Geo? Was the Neo Geo really just a glorified Genesis given its VERY similar hardware? (think of how the Wii is mostly a glorified Gamecube).
Sorry for the massive wall of text, just wanted to make a very detailed post regarding the aspects of each console. All information taken from Wikipedia.