This is sorta my canned answer to this question...
Really, with shotguns, it comes down to proven performers. Designs and contenders come and go but some models have real staying power and there's a reason for that. They work, and they work well.
In Autos, if you're wanting bullet proof reliability, there's really only one way to go and that's Benelli. If you don't want to spend the money then don't go auto. I've seen people own 1100/1187's that worked OK but I've also seen and shot with guys that couldn't get them to work worth a damn and had to dump lots of money into them and at the end of the day they could have just bought a garden variety M2 with rifle sights and had a better gun. That's not to say that other guns aren't nice, or that other manufacturers don't produce nice guns but when you see people who are knowledgeable and are concerned with having bulletproof reliability in an auto, most likely they've got a Benelli.
In Pump guns it's really about the 870 or the Mossberg 500/590 series. Sure there are others but those two have the lions share of the market for a reason. Of those two I can go either way between the 870 and the 590A1 although I'm not a huge fan of the base 500's. It comes down to ergonomics and what you plan to do with it. If you like a pistolgrip stock go 870. If you like the standard rifle style stock either will work well.
Either of those two pump guns will last the rest of your natural life with basic upkeep and either should fire well with anything you put through it. Both come with a huge variety of sights, stocks, tacticool goodies, etc.
A note on Benelli price:
I bought my Benelli new from Sportsmans Warehouse for $875 on clearance. It had the (highly undesirable lol) rifle sights so it was marked down because all the mall-ninja kids want ghost rings. I further was able to capitalize on the mail in rebate which Benelli offers once a year. I believe it was $200 but it may have only been $150 on the M2. I also got 5% off because I'm a vet and Sportsmans Warehouse is cool that way.
So you can see that for around $700 I got a brand new Benelli M2 with an 18in barrel and rifle sights. Obviously that's not a deal everyone gets, but it's not crazy either.
All I did was the Daves Extension and an Urbino stock and it's fully good to go.