Pretty much all of the big players that were still around in 1993 or 1994 had 2MB graphics adapters. I personally have owned quite a number of ISA 2MB or 4MB cards, but mostly with S3, ATi and Tseng chipsets. Though Cirrus Logic also had 2MB cards. Supposedly the ones based on the CL GD5434 chipsets are quite good.
It's not quite true that there are no advantages to having an ISA card with more than 1MB. If you only play DOS games, 256KB or 512KB is probably all you would ever need. But more memory makes a huge difference for Windows applications, especially if the card uses graphics acceleration. The Mach8 was one of the first chips on the market which offered this (though did not always have VGA, such as yours).
I think others in here have probably already explained how accelerated graphics can help overcome the bandwidth limitations of the ISA bus, by speeding up the way various line draws are performed. You can think of it as bitmapped graphics (VGA) versus vector graphics (8514). Windows 3.1 is an environment where accelerated graphics makes a HUGE difference.
As others have said, having lots of memory helps tremendously with screen resolution and colour depth. Windows 3.1 doesn't really make good use of 256 colour graphics. Personally I find the windows dithering revolting. Having 15-bit, 16-bit and 24-bit colour depths makes the win31 experience so much better. Though you have to keep in mind that there are also quite a few win31 apps that make extensive use of 256 color cycling that won't run under other colour depths.
My all time favourite ISA card for windows is the Mach64 VRAM. The 2MB version is probably all you'll ever need. It offers 1024x768@16-bit colour. I have the 4MB version, which can do 1600x1200@16-bit colour, but it's really too slow to be practical. Probably your best bet is to pick up that CL GD5434 card I mentioned earlier. They're usually not too hard to find, and pretty cheap. Great DOS performance, as well as pretty darn good Windows graphics, and yes it is an accelerated DRAM chipset.
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