If You bought a costly 4k TV then you should definitely go for Private DTH or Cable. DD Free Dish still using MPEG-2 format and that will cause masiv pixelation on a big TV.
While DD Sports HD quality is good and comparable with Star Sports HD.
If You want to go for DD Free Dish only, then buy any Solid box. New box(Solid 61XX Series) is not much recommended as they have bad software. Solid 6363 has a very good software experience, You can also consider this.
If You want to buy any set top box then buy from local market, You will get major difference between online and Local price.
Lripl boxes are very good at low cost.
The new box lr26i that claiming no antenna for channels is a fake product. They are basically providing open source GitHub IPTV m3u in it and most of channels will not work. And also they using same motherboard in this box and LR777. If You getting it around 600-700 then it's a good choice. Don't expect very good PQ at this price range.