I'm going to go against the grain here and say Hillary is the slight favorite.
Let's consider the following factors:
1. The nation was and is extremely polarized along partisan lines; it seems there is little either party can actually do that has a major impact on voting patterns either way. And in general, Democrats are favored to win the popular vote and at least come close to winning the electoral vote since 1988; the nation as a whole is D +2/3 right now in a neutral environment, not entirely even. So all else equal, you should assume the Democrat is going to get more votes and go from there; I am totally skeptical of claims that Pence would have EASILY beaten her even though he could have won due to the increasing split between the popular and electoral vote.
2. Trump largely avoided ever sinking to all-time lows in popularity mainly because of both number 1 and because the economy was still pretty good for the most part under his presidency; there is little reason to think that would have changed much for the worse with Hillary.
3. Combining 1 and 2, and taking it as a given that Hillary obviously won the popular vote by at least as much as she did anyway AND probably won the EC by about as much as Biden did, at least, it's not hard to imagine that her approval ratings would basically be a mirror of Trump's, much like Biden's are now.
4. Most world leaders and even US governors saw a boost in their popularity and electoral fortunes following COVID; Trump was uniquely unmoved or even damaged by the pandemic in that regard, and given it's almost a certainty Hillary would have handled the pandemic FAR better, it actually could have been a boon to her.
5. Incumbents are generally favored, and Trump came very close to continuing that pattern and winning again despite everything, and probably could have if not for a few major blunders on his part that Hillary almost certainly would have avoided.
6. Mike Pence is an extremely boring man who would not at all rile up the GOP base in the same way that Trump did, which was JUST BARELY enough to win once (and wasn't enough to win again) anyway. Thus it is not hard to imagine his campaign would more closely resemble Mitt Romney's 2012 campaign than either of Trump's.
7. If the GOP aggressively obstructed Hillary at every turn, even when it came to things like SCOTUS appointments, as they suggested they planned to do (leaving a seat open for four years!), that is likely to exasperate swing voters. Likewise, most of the fear-mongering they did about how Hillary was all but literally the devil would have proven untrue quite quickly under her administration; voters would have seen how benign and banal she really is and become accustomed to her, perhaps even taken a shine to her, after four years. Major contrast to Trump who basically confirmed everything the Democrats warned about him every day with every Tweet, etc.
As a result, I think the following is the single most likely map, give or take a few states:
