Sorry, but post in this thread:
http://gbatemp.net/index.php?showtopic=70252
It's a thread designated for flashcart suggestions!
Also, I searched and it took me few seconds to find this thread too:
http://gbatemp.net/index.php?showtopic=94838
Thread reopened, because OP contacted me, and he would really like to hear current opinions on the EDGE and M3 Real..
In my opinion, M3 Real is better because it has the most beautiful GUI currently made for flashcarts, especially if you used multimedia with your NDS, as it has integrated DPG player, MP3 player, text reader and picture viewer..
If you buy Perfect Pack, you'll get the GBA expansion slot2, and you get the most powerful solution for GBA games (with GBA RTS and Cheats for GBA)..
On the other side, if you don't use multimedia with your NDS, and you don't care for GBA games or graphic interface, EDGE is a great cart too, simple GUI but very nice and responsive..
Both carts have great game compatibility, and shouldn't cause you any problems with that!