My notions of Bush evolved. But one could make the case that Bush himself evolved over his eight year tenure. It took him too long to recognize that Cheney had not been a good influence and he possibly came to recognize the same about Rove as well. He came to understand, I think, that he'd been used.
Initially, we didn't think well of Bush because of the manner of his assumption to office. That seemed a consequence of take-no-prisoners power politics at a pretty ugly level - ugly enough that the SC majority chose who would be President. But even prior to that point, Bush seemed woefully unprepared for the presidency, who was under the pretty constant care of handlers so that he wouldn't say stupid stuff in public, who seemed poorly educated (his favorite philosopher was Jesus), and who had a depressingly poor familiarity with the world outside the US (or even with the world outside of very privileged America). And there's the similarity with Trump. Bush, originally at least, was out of his depth in that office and it showed in all sorts of ways as it does with Trump.
Then 9/11 and American politics went really nuts. If I remember correctly, it wasn't until near halfway through Bush's second term that he began to act independent from Cheney's office and from the other power centers in the party at that time (neoconservatives, even the Christian right). The bombast was gone or turned way down, the deceits diminished, and a more sober and honest reflectiveness emerged.
But it has really been his demeanor since leaving office which most deserves respect. In this period, he has shown a level of character which, by way of contrast, remains totally absent in Dick Cheney. And one can (at least I can) see in Bush a real empathy for others which I've never seen in Rove.
But Trump is never going to be reflective. He's never going to feel much empathy for others. He's never going to have "character" because that word and attribute refer to honesty, to transparency, to consistency, to dependability and to an innate sense of community membership.