Since my buddies and I run (or used to run) medium-high power early 90's machines (1991 Mach Z, 1990 Indy 650, 1993 Formula SS?, 1993 Wildcat, 1995 XLT 600, 1994 Indy Storm, 1998 ZR500, 1988 Phazer II?, 1992 Phazer II?, 1988 Excel III (low power/slow), etc. I've often travelled with many other machines, including some 90's V-max's etc.); here are some generalities for those years I've noticed (IMO):
Bombardier (Skidoo) - most powerful & responsive engines, best straight line acceleration (stock), lift the skis too much (the 1991 Mach Z is terrible for that), relatively poor handling on twisty trails, typical snowmobile maintenace requirements (extremely high compared to any other type of motorized vehicle).
Polaris - best overall handling & feel (I do own one though so I'm biased - a 1990 Indy 650), skis stay on the ground (more often), decent suspension for bumps (7.5" of travel), fastest on the twisty trails. typical maintenance requirements (or slightly higher).
Arctic Cat - best suspension for bumps (? travel, but more than Polaris), good handling, very high power machines (Wildcat & T-cat) are very heavy and handle a little worse, but really move. Typical maintenance.
Yamaha - average handling (or slightly worse), average suspension (or slightly worse), a little less power, but much more reliable than the other 3 manufacturers.
Throughout the 90's all improved (this is based mainly on magazine reviews). The newer Bombardier's have much better handling, the Polaris's have made major improvements to the suspension for rough trails (more travel), the Arctic Cats have continued to improve overall with lighter high performance machines available, and Yamaha has made major improvements to handling and is still the most reliable (and have the best warranty).
Keep in mind that although I've been sledding for about 21 years these are not "expert" opinions, just my personal experiences (I have tried out each machine above for a couple of hours of trail riding except the Storm).
If you're looking at newer sleds than 1994 you're probably best to read some magazine reviews or ask around some more. I can tell you my friend's 1998 ZR500 handles as well as my 1990 Indy 650, it's just as fast (almost), has much better throttle response, and is about 10 times more comfortable on rough trails - no to mention the incredible headlights and with the low miles little maintenance requirements (so far).
Around here (Ontario, Canada) you can pick up a reasonably high performance early 90's machine in good condition for $2000-$3000 Cdn. Typically if you pick up one that needs lots of work, you'll end up spending close to that anyway. One friend recently picked up the 1998 ZR500 for $5000 Cdn with only 1000 miles on it.