You don't mention which model within the E-Series you're looking at, so I'll take a shot that you mean the basic, non-railed, non-commander sized model. Side by side with the loaded, it's a tough choice, so the advice above about buying the cheaper one first makes sense. Particularly when you consider that you'll likely own both eventually.
I will say, however, that of the two, for me, the S&W is a more attractive option. I still say they are the most underrated of the 1911s out there. I really like the overall quality and the extra touches that come standard on that series. As far as reliability and accuracy, you won't be disappointed by either pistol. I cannot speak to customer service support, because I've never used either. Be that as it may, I hear good things about both, if that's important to you.
The E-Series extras I really like are the frontstrap checkering, the slide top serrations (reminiscent of their revolvers, for us wheel-gunners), the flush-cut barrel, the angled cuts around the ejection port, and the extra large claw on the extractor - take a look at that thing, it's massive. Overall, it's a fine package, and at it's price point, it's an absolute bargain. The loaded is no slouch either, it just has fewer extra touches, ambi-safety aside. As for sights, that's strictly a personal preference. I wish Smith would issue one with adjustables, but that's just me. Again, you can't go wrong with either model, and eventually, you'll likely end up with both
