On that budget you're going to have to compromise on something.
Televisions 70" and larger are niche so they are often much more expensive than 65" models. A 70" television is so big that with normal television content it is going to show up lots of source material flaws unless you sit far enough away from the television or engage lots of noise reduction.
Best resolution and refresh rate would mean a 4K television with HDMI 2. You won't find a 70" with those specifications for under US$3000. While 4K content may benefit from the extra size, there won't be much 4K content for a while so you'll still find yourself mostly watching HD and SD.
It'd be better to buy a 4K television later in the year when prices have dropped and new models have come out. Or buy a 60" to 65" 1080p to use until 4k matures.