For normal TV viewing at 10 feet away 42" is big, 37" is better IMO. The tuner in the TV makes a big difference to quality. For DVDs 42" is great, for HD you could certainly go bigger up to 50". So depends on what you mostly watch.
The Sharp is LCD and gets OK reviews, the TV tuner is not great though. I have a 42" Panasonic PX70 plasma which is fantastic for TV or DVD etc. I think plasmas have a more natural photographic look, do dark scenes and handle motion better. Downside of plasmas is the screen is reflective glass whereas LCD screens are coated and less reflective, so if you want to watch a lot in the day and you have windows behind you it could be a problem.
I would consider Panasonic, either HD ready or full HD models, Pioneer ditto, all plasmas. Top of the range Sony and Philips models as well as Sharp for LCDs. If you believe magazines they all say the new Pioneers beat everything but are expensive.
Buy decent cables whatever screen you buy - I've tried QED and Chord in scart, component and HDMI and Chord is a wonderful improvement IMO. And set the screen up carefully, the settings from the box are always horrible.
Good luck