My first shotgun was an 870 Express Magnum, it worked fine, just the finish tore up my rags and I had bits of cotton all over the gun, and wiping oil onto the finish was a PITA. Otherwise, the gun was great.
I sold it, and got a Mossberg 500, lefty. It's been so reliable and all the features they give you (3 chokes, sling studs etc.) make it great out of the box. It isn't pretty, but it's modular, parts are easy to swap out and fix if necessary, and it's affordable. The gun isn't cheap, it was designed to a certain price point and Mossberg meets these requirements well in their design, it was a well thought out platform.
I bought a '72 Rem Wingmaster recently and it's nicely blued, locks up tight, is smooth. I put a 12.5'' barrel on it for fun. Lots of aftermarket. I like both and they each have their own roles in my safe. Mossberg for hunting due to light weight and long barrel. Rem for training, tactics.