Yep, like I said...it's enough to make your head spin and it's pretty much impossible to keep much of it straight when you've never worked in a job like this before. The OP asked specifically for pros, and not cons. Certainly there are cons as well. I'll throw in my opinions on some of those brought up.

I don't think it's fair to call ready reserve abusive. Is it as good as short call? No. Is it as good as flying? No. But, you're being paid for an airport sit. No matter where you go, you'll have a lot of airport sits. A lot. A whole lot. And you mostly won't get paid for them either. Nine block hour, 6 leg, 14 hour FDP days in and out of IAH through thunderstorms in a 200 with a deferred APU in the summer is abusive. Reading the latest novel, watching Netflix and playing Pokemon Go in the airport for 8 hours isn't abuse. It's one of the easiest jobs ever, outside of being a pilot. I wasn't forced to spend years on reserve. In fact, I probably could have gotten away with about 10 weeks total on reserve but I thought reserve was so easy living in base that I bid it for another 3 months before deciding to bid for a line. But, to each his own. Certainly there are some folks who really despise ready for whatever reason.

I'll agree with the poster above that Republic's and Endeavor's pay overall is probably a little higher than SkyWest's. Again, there's so much variance depending on which base you are at. Some will have a lot of open time and incentive pay for that open time. Some will get you right out of reserve and off to 95+ credit hour lines, etc. Some will have you making reserve guarantee for 9 months. It's probably fair to put SkyWest third behind 9E and YX and ahead of the rest.

As far as travel benefits, we probably split the two. Republic adds American, while we typically only get 2 of the 3 legacies to nonrev on. Endeavor does get the wholly owned bump on Delta, but I always found Delta much harder to nonrev on than United, at least domestically. Maybe I've just had really bad luck, but there always seems to be 20-30 standbys listed for 3 seats on Delta, while United's standby lists are like 5 for those 3 seats and 2 people don't show up or misconnect. That's just my own personal experience and anecdotal for sure, but as of now I'd rather have my current benefits than a slight bump on Delta.

Commuter hotels - yep, we don't have them. That's a con. Well, it is if you plan on commuting for a long period of time, which I highly discourage no matter what airline you decide upon and whether they have commuter hotels or not.

Commuter positive space clause - meh, I guess so. The problem is for the airlines with these clauses you get in really big trouble if you don't give yourself the 2 or 3 flights to get to work on time, even if you hardly ever actually miss work. At SkyWest, you really have to miss a lot of commutes before there is any tangible punishment.

Republic has 12 bases all on the east coast and OO's, while we have more, are scattered across the country. Yes, true. Whether that's a pro or a con I suppose depends on the person. If you have no desire to ever head out west, then Republic has more bases on the east coast, and they are a great company to work for as well. I wouldn't fault anyone for choosing Republic if they lived in a junior Republic base and wanted to stay there. So long as you want to be east coast, many of the pros for OO also apply, at least partially, for YX as well. 9E only has 6 bases, but they are also all on the east coast, so it's fair to say 9E has more east coast bases than OO, if that's where you know you want to stay.

Edit: One of the biggest cons a lot of folks see in OO is that we're not unionized. A lot of people feel that a union is necessary and not having one is a huge blight on your company. Others look at Mesa, TSA, GoJet, Compass, and Piedmont and decide that having ALPA at a regional doesn't mean it will be a good place to work. Of all the hate that SkyWest gets though, this is the biggest source.