Ya at least for now compactness is the big one. Basically forcing cleaner maps would ensure that commissions have fewer tools to gerrymander in favor of Dems while claiming they are following some neutral principle.
Which btw is basically 100% of the reason Rs are opposed to a national redistricting amendment - Dems have proven significantly more adept at gaming the system on ‘neutral’ commissions and using that as a back door to pass soft gerrymanders that bypass the state legislative system. If you truly don’t like gerrymandering (and no one should), then it is disingenuous to say that Ds ‘want to fix it’ when their proposed fix really just means giving them an advantage everywhere.
Basically, it comes down to people who think we should have a fair way of drawing the lines, and people who think there shouldn’t be any lines at all and therefore any method to draw unfair lines that arrives at a similar result as to no lines is therefore good. I’m personally in the former camp, though I understand the reasoning of the latter camp.
The maps produced by commissions almost all have a small R bias. The only exception I can think of is California.
California is the only map that was produced by a commission that favored Democrats more than their proportion of the statewide vote, and that's really more due to California's geography being terrible for Republicans and California having such a large Democratic lean.
True Compactness wouldn't really favor Republicans all that much anymore, especially in southern states like Georgia or Texas. Compactness doesn't just mean making small inner city districts and then drawing the suburbs out to the rurals, they'd need to make the suburbs have their own districts which would favor Democrats quite a bit, especially in the long term.
What I will say is that the Central Valley seemed to be awfully drawn for the 2012-2020 races. The hooks around Fresno and Bakersfield are terrible. CA-16, CA-22, and CA-23 are awful.
Not going to touch the LA area since I’m not an expert in city boundaries there.
Down in San Diego, CA-51 is pretty bad.
