Not everybody thinks he was the worst president ever. Many historians give him a mid-level rank.
I give him a lower-middle myself. It will be interesting to see how he is viewed a generation or two from now, when historians actually have had time to judge him.
Well, for starters, capturing Osama shortly after the invasion of Afghanistan, avoiding the Iraq War or else changing how it is carried out and a better federal response to Huricane Katrina.
The first is easy, the second possible but rather out of character for him, and the last wasn't his fault in the first place.
With a PoD in 1994 or later? Clinton, while still POTUS, takes one of the several chances he had to kill OBL. There is no 9/11, no Patriot Act, no invasion of Afghanistan, no Global War on Terror.
Bush picks someone else as VP - someone not terribly well known, but well-spoken and with a good moderate track record. He wins 2000 clean after his VP candidate trounces Lieberman in the VP debate, swinging about 1% of voters - enough to give him a win in the popular count as well as an uncontested win in Florida. Gore still protests and demands recounts, but Florida keeps coming up clearly for Bush each time. Gore is discredited, and Bush looks good by comparison.
Bush has some small but notable and popular victories in his first year in office (tax cuts, a few token medicare reforms, etc.). In 2002 Saddam starts another offensive against his Kurdish population, again using chemical weapons as he had before. A plane goes astray and a mustard gas bomb is dropped in Turkey. Several children are killed.
Bush sees a chance to finish what his father didn't, and takes it. With a limited international coalition (most NATO powers, pressured by fellow member Turkey, contribute token forces), the US smashes Iraq. Saddam goes into hiding, and is captured in early 2003. There is a large uptick in Bush's popularity numbers as a result.
Then, late in 2003, Bush is assassinated. As is typical in such cases, his memory is always colored with a sympathetic lens for being cut down by a madman while still in office.
The Democrats win in 2004. The economic recession hits a bit earlier in 2007 (no turbulence from 9/11), and many people blame the new administration. The positive (though unimpressive) economic growth while Bush was in office looks much better in contrast to the 2007 crash.
All in all, very unlikely, but that's as close as I can get to Bush being remembered as a great POTUS.
Edit to add: forgot to put in, the Dem POTUS elected in 2004 also looks bad when FEMA is criticized for the response to Katrina in 2005. Again, Bush looks better because his successor looks bad. Not fair, but common.