I get the impression that you have about equal chances of getting a rude gate agent no matter what airlines you fly with. Which is to say they're almost all reasonable people, but sometimes have bad days, other times it depends more on how you ask. The guy here seems to have an entitlement. He's a frequent flyer, his kids aren't, he was asking if they could get on with him in the early boarding. He could have paid the early check-in fee for them and gotten on before most people anyway. I think it's $15 on southwest. Point is, he had other options. It's fine to ask for favors, but if you're fuming about someone NOT granting you a favor, you're probably the asshole in that situation.
Moreover, personally, I'm willing to pay for more polite staff. Specifically, I'm willing to pay maybe five dollars.
Southwest is still cheaper usually. Who cares about rude gate agents?
On service (as in flights on time) I have gotten the impression that they're slipping.
Their fleet isn't as young as it used to be. Mechanical issues seem to be causing more delays. That said,
they're still newer planes than Delta. I suspect southwest's reputation is working against them here: If Delta is delayed 2 hours you think "Fucking Delta, always pulling this shit, good thing I brought a book to read just in case this happened." If Southwest is delayed you think "WHAT THE FUCK!!! SOUTHWEST ISN'T SUPPOSED TO DO THIS SHIT!!! AAAAA!!!!"
I may be biased though because Delta woke me up in very the middle of a trans-pacific flight to fucking sell me duty free shit, and I didn't get back to sleep the remaining 6 or so hours, then on the ground I learned they had smashed both of my checked articles, and then told me with a straight face that I took that risk when I checked it. Southwest doesn't do international flights, so doesn't have a chance to wake me up trying to sell me something, and I don't check bags anymore.