at high altitude supposed problem is largely behind us. Yeah, hype kept me away for that very reason in 2003 when I suddenly needed to replace a TV. I had been out of touch & perhaps could have gotten some education if I had asked questions of dealers.
However, for that very concern, plasmas were re-engineered & you can chase down some company data of their certifying up to what altitude. What particular altitude, I don't know. I only live at one mile (Albuquerque.) Nearby Santa Fe is your altitude.
It is worthwhile tracking down that data from manufacturers websites. The reason is, consensus of opinion by watching plasma & LCD side by side is that the plasma picture is overall more satisfying.
Samsung had been a smaller seller, but has been comprehensively aggressive & now is a first rate line & the best selling brand, surpassing Sony. Of your mentioned sets, folks here would steer you towards Samsung, & probably make a point of steering you away from Sharp, who put out some deficient products.
Most here also advocate staying with the name brands. I concur. My next set is likely to be a Panasonic plasma. They are regarded as putting out the best value plasma sets. Their newest sets have much improved black levels & use less electrical juice than plasmas have gotten a rap for when compared with LCDs. All that mentioned, you will notice online & in the stores that the makers are now giving LCD a big push. Apparently if they get maximum volume production of them there are more profit margins for them. Don't let that deter you from getting what you decide you want.
I don't really have anything against LCD sets as this computer has one as well as our secondary set is an LCD. I just do believe I definitely prefer plasmas "softer" picture for the big, main set.