I've used a TI-86 since high school (8 years) and so far it's served me well. The only time it's been banned from use is when all graphing calculators are banned, but I've had friends with 89's who've not been able to use their calculators on multiple tests. The 86 doesn't have all the bells and whistles the 89+ have but isn't banned as often and does have a leg up on the 83 series.
I've used a TI-86 since high school (8 years) and so far it's served me well. The only time it's been banned from use is when all graphing calculators are banned, but I've had friends with 89's who've not been able to use their calculators on multiple tests. The 86 doesn't have all the bells and whistles the 89+ have but isn't banned as often and does have a leg up on the 83 series.