Ez-flash IV, and it was a good choice, because I got to play heaps of GBA and NDS games
Been through 2 of them and unfortunately, both are software bricked...
I can however still use them to play gba games with the slot1 gba loaders (such as rudolphs), but I don't even play GBA games anymore (I beat most of the good ones), let alone NDS games. And unfortunately all that NOR memory can't be accessed through rudolphs loaders either... It'd be nice if it even worked with EZ5, but they only support 3in1 nowadays.
I always wanted the original acekard (loved the ui and design), but i guess it was fortunate that I held off. Given my affiliation with bamboo gaming (Did some shop forum moderating and reviews) back in the day, they gave me a few flashcards so I had a couple of slot 1s including ak2, akrpg, ezflash5, supercard (original), G6Real, TTDS, M3Real, Edge.
I gave my bro the edge and sold the M3Real + a microsd to my best mate (on the cheap because he's my mate). The rest sit around my room, hardly in use at all. Most of them also suffer contact issues :S And I use the AK2 with my DS because it's the most reliable. I might try the new supercard OS with my supercard if it's compatible with the old ones... (is it?).