I am looking at buying the Dynex DX-L42-10A or the Insignia NS-L42Q-10A. Which one do you think I should get?
Your really asking which one is worse? Both. Dynex have a high failure rate, there considered throw away tv's and Insignia has the worst customer service bar none, there tv's also don't last, that's why they doubled the warranty, so they can fool customer's into thinking they got a great deal.
The only reason you should even consider these brands is if you have a best buy gift card that is expiring soon and you must use it or lose it, otherwise, shop elsewhere.
Both of these TVs are Best Buy store brands. But 90% of the time, anything you buy is going to be made in China regardless of the label, and much of the time the same components go into all the "different" TV brands in the same Chinese factory. The suggestion that these TVs are "junk" is bunk.
The big difference is refresh rate, and at the moment most Dynex and Insignia TVs are at the lower, 60Hz rate. That is the major price point that separates a $600 42" LCD 1080p Dynex TV from another brand's $1200 TV with the same configuration except for a 120Hz refresh rate. All of these TVs should last for years and years despite the naysayers above. Unless you get one that is used, it is difficult to buy a poor quality HDTV these days, and Best Buy has a generous return policy for any defective products that they sold. As for me, I think my 42" 1080p Dynex is great.
I have a 22" 1080p HD set and a Blu-Ray Insignia player and both are working fine. For support they have a website forum where you can get assistance, http://community.insigniaproducts.com/insignia/. And for an extra CYI, I charged them on charge card which doubles the manufacturer warranty so the TV's covered for four years.