Well, the 4th generation chips are lousy no matter what brand you get. The 5th generation in LG or Samsung flavors have had very good reviews. LG is considered the best. The 6th LG chip, LG claims, is even better. Exactly why it is better only LG knows for sure. There is no way anyone can explain to you a trade secret that LG does not share with the world. They are not going to publish the schematic on the Web. I just wish LG made a real full HD tuner with it and not just a cheap converter box. My 3rd or 4th generation ATI chip in my RPTV is just not good enough for the task at hand.
By the way, it is my suspicion that the US Government will have millions of left-over coupons. I do not think the demand will be that great, and I think allot of people will get them and never cash them in on a box.