The best TV I have in my house is a 13 year old, 42" Panasonic 480p plasma EDTV. Everything looks great on it: 1080p blu-rays are scaled down and look great, 1080i HDTV looks fantastic, DVDs look awesome at their native resolution and even old, lower quality, 512x218 DIVX/XVID AVIs and standard definition TV channels are watchable. Also in the house are a later 32" 720p Panasonic LCD TV and 50" 1080p Smart TV by LG that I was going to use to replace the old EDTV, but it’s just not as good.
When all my content is 4k, I’ll want a 4K TV, but for now, that 480p is great because scaling down always works better than scaling up…