Major Airlines
Delta Air Lines: 5.00 (Grade A)
Frontier Airlines: 4.80 (Grade A)
Alaska Airlines: 3.85 (Grade B)
Allegiant Air: 3.65 (Grade B)
Southwest Airlines: 3.30 (Grade C)
Hawaiian Airlines: 3.15 (Grade C)
United Airlines: 2.70 (Grade C)
Spirit Airlines: 2.05 (Grade D)
JetBlue: 1.80 (Grade D)
American Airlines: 1.75 (Grade D)
Regional Airlines
GoJet Airlines: 3.85 (Grade B)
Piedmont Airlines: 3.05 (Grade C)
Sun Country Airlines: 3.00 (Grade C)
Endeavor Air: 2.95 (Grade C)
SkyWest Airlines: 2.40 (Grade D)
Envoy Air: 2.30 (Grade D)
PSA Airlines: 2.25 (Grade D)
Air Wisconsin Airlines: 2.15 (Grade D)
Republic Airways: 2.05 (Grade D)
CommuteAir: 1.60 (Grade D)
Mesa Airlines: 1.35 (Grade F)
[edit: formatting]
And also every time there's a report, they rank this way
I always take my suitcase and my backpack to the airplane and then I check my suitcase at the gate. Three reasons. First, there are no baggage fees at the gate. Second, I can roll backpack on my suitcase. Third, I get to board early for "helping out". Why wouldn't you do this?
I do only check it if someone else in my party is already checking bags but that turns out to be most of the time for me.
Note: I'm actually replying to a reply that's too deep.
Normally gate checking is the better option, but you can't do it when flying with stuff that can't go into a carryon: bottles of wine, firearms, and so on.
YMMV, just my $0.02