There is no inherently best flash card, all depends on one's expectations (of price, intended uses, and consoles to use it on)
This one (as well as its direct predecessor with a green and black sticker, also branded r4ids.cn) are widely agreed to be the best general purpose DS flashcards, suitable for both ntrboot use, and running DS games, with excellent compatibility, on any DS-compatible console (even unmodded)
You can in fact run commercial DS games on a modded DSi or 3DS (using TwilightMenu++ and nds-bootstrap) but compatibility and ease of setup are inferior (as of today and probably for a decent amount of time in the future)
Okay thank you - I take it that you recommend getting this card then?