I recommend 98 or 2000 for a starter. (2000 will really hook you to the series). after getting 2000, try 2001.
I arranged it according to gameplay. so unless backgrounds, animations, music ....... etc. you can't get wrong with this order.
if you are really interested, I can show you some good combo stuff for 2000, 2001 and 2002. just let me know.