They are all basically the same bike. Although, I've heard the 85's exhaust didn't meet the imission standards, so it changed shortly there after.
As far as some of the other changes they include; beefier forks, colors, and Yammaha's version of the o-ring fix and 2nd gear fix.
Here is a list of changes:
Vmax Changes from 1985 to 2001
First V-Max appears on American market with 145 HP announced and 1/4 mile covered in 10 seconds. V-boost equipped.
Introduction for Europe in France:
104 HP at 7 500 rpm and a torque of 11,48 mkg at 6 000 rpm
No V-Boost for Europe
Rear aliminium dished wheel
2 front ventilated discs ? 282 mm with opposed pistons.
3D V-max emblem
Front aluminium dished wheel
Black air scoops, side covers and tail lamp mount
Digital electronic ignition.
Back to aluminium colour for air scoops
Introduction for Japanese domestic market
Modifications to suit noise regulation from 83 to 81 dB. Exhaust system changed and max. power decreases from 100,2 HP/ 7500 rpm to 95,2 HP/ 8000 rpm.
New camshafts with lengthen valve opening to improve character: Max torque of 10,3 mkg is at 3000 rpm only ( formerly 10,9 mkg / 6000 rpm). To keep superb acceleration rear transmission, ration is changed from 33/9 to 33/10.
Fundamental chassis changes:
Fork tubes increase from 40 to 43 mm. Ventilated- drilled discs of 298 mm with 4pot callipers.
Metzeler tyres instead of Dunlop.
More powerful generator.
Black wheels ,air scoops, exhaust system and fork outer tubes.
Cartridge type oil filter element
Back to chrome exhaust system
Back to polished wheels and fork outer tubes
Carbon look for fenders
Front fork seal guards
Carbon looks for tank cover
Bur to answer your title question, 2007 is the best year
1990 all the way just cause that is what I ride!! lol Really I have found evidence like my seat has 2 different years marked under it and neither is 1990 but hey it runs super and looks awesome. What more could you want
Oh ya My bike is Blacked as well so ya its better and faster lol