I have owned both over the past two months. I liked the Vizio a lot when I first got it. Color and overall screen quality, particularly right in front, is extremely good. Mine suffered lip sync issues but it was random enough that I was just putting up with it when it occurred. Unfortunately, after about a month, the picture stopped displaying an image though I could tell at least some of the LED's where still on (dark gray screen, not completely off). I also continued to hear audio. Anyway, back it went...and, I have to say, the incident with both the lip sync and final failure made me a bit gun shy of trying another one.
Fast forward to last week when I picked up the Sharp. I think the picture overall is a little better than that on the Vizio. Better blacks and slightly better off angle viewing. The surface is a little more matte than the Vizio. I did, for whatever reason, have a much easier time dialing in the color on the Vizio vs the Sharp (even though the Sharp has a lot of fine color controls). Main issues I have experienced with the Sharp:
1) Terrible soap opera effect with motion out of the box. Turning off all motion effects does not completely fix the issue. Thus far, the only solution I have found is to use the Game mode, which has two drawbacks. A) It cannot be used when watching the built in Apps such as Netflix. B) it's much more difficult to calibrate - and I'm not sure yet it can be accurately calibrated - as the Gamma is out of range as compared to the Movie mode (which, again offers no way to fix the motion issues).
2) At least on my unit, the built in WiFi is extremely weak to the point of being almost unusable. In fact, I can only get it to connect if I remove the security feature (password protection) from my wifi. With password protection enabled, I only get error messages when inputing my password and attempting to connect (WPA). I even went so far as to purchase a dual band (N+G) router to see if it might be my wireless router. It's not!
3) Arg! I have also experienced lip sync issues at least on one occasion with OTA HD (optical out to receiver). Never an issue with my prevous TV and same connection.
So, unfortunately, the Sharp is likely going back as well. I have no idea what I'm going to buy at this point to replace my seven year old 32" Olevia LCD.