I've the Ashley on my Marlin 1894, a friend has the Williams on his Marlin 336 (oh man, you should see the wood his new gun came with, gorgeous!), so a quick comparison.
Ashley is small and very tough (need for wings is debatable, I'd be more concerned about the front blade). I didn't like the front post that shipped with it, so bought a new front sight blade (Williams Fire Sight, 250N .406 high, $16) that fit in the factory ramp. Works like a charm. Ashley are for close work as even the small aperature is BIG. Offhand, I get nice tight groups up to 50 yards, 100 yards are a challenge.
Williams receiver sight is very nice. Quality part that screws right on. Many aperature sizes; you can get the pinhole one so you can dot the "i" at 100 yards. But it looks fragile (looks, don't know if it is). This is a sight for a serious paper puncher or long range hunter.
For a close in hunting gun, I'd say the Ashley is fine. If you want to reach way out and touch something, its ill suited.