Ronald Reagan, had he been able to, probably would've won again in a landslide in 1988. In the mid '80s, after his '84 massive victory, there were quite a few Republican operatives who wanted to try to get the 22nd Amendment repealed to ensure a third term for Reagan. Reagan himself felt the 22nd Amendment should be repealed as it limited the freedom of voters.
That said--If it had been repealed, would you have voted for Reagan in 1988 if he would've run? I believe that if he could've run, he would've, and would've won easily. According to all of his doctors, the first overt signs of Alzheimers didn't began to show themselves until late 1992, and he wasn't formally diagnosed until mid 1994--Therefore he didn't show any major symptoms of the disease until what would've been the very end of his 3rd term.
Being over 80 years old by 1992, he probably wouldn't have sought a fourth term even if he could legally, so there would've been no danger of his declining mental health putting the country at risk. Watch his stump speeches for the 1992 campaign--While his speech isn't as forceful, quick, strong as it was in 1980, he was obviously still very much in command of his faculties for a man of 81 years. Even in 1992, he could still out match many younger, modern orators. He likely would've kept Bush on if he ran in 1988, so even if he died (which was unlikely given his great physical health) sometime during his third term, we'd still have gotten President Bush and history would've continued as it was in our favor.
So all that said, if you could've, would you have voted for Reagan again in 1988?