I dont know if thats really even the standard anymore. Sure, the 95 M3 engine is easier to modify but there are so many aftermarket parts out there that OBDII are becoming jsut as easy to modify. A big thing about the ODI's though is the simple 3.5" intake+HFM+injectors+tuning modification that will give great and easy yeilds.
If you're looking just find the nicest, cleanest e36 in the best condition with the lowest miles that will all work within your budget.
1995 BMW M3 Turbo - Dakar/Black