The EZ-Flash IV seems to be the most highly recommended, but it might be difficult to find one nowadays, at least one that actually plays all GBA games (rather than the versions that only play games up to a certain size). Following that would be the M3 Perfect (not Pro) which may also be difficult to find. The non-Rumble Supercard would probably be the easiest to find, and cheaper than the M3 Perfect, but then you get slowdowns in some GBA games so it's not a very good option.

 

EZ-Flash IV is still easy to find.

http://www.dealextreme.com/details.dx/sku.11179
http://www.realhotstuff.com/ezflash-size-p-294.html

It will take up to an 8 GB SD card. Mini SD isn't very common, but many Micro cards come with adaptors. As far as compatibility, it's high. Mother 3 requires being moves to NOR, though. I've played through Castlevania HoS and Metroid Zero Mission with no hassles.

You'll miss out on the rumble and RAM of the 3-in-1, but this will work in all GBAs, DS, DS Lite, and Gameboy Player, advantages I consider important. I'm mainly using it in my GB player anyway.

My only gripes? The firmware updating is a bit annoying, it's more than a hassle to update the damn skin on the thing(by default it has a Star Wars Ep 3 skin) and you'll have to use a loader program to put games onto the card, which renames everything. It also lacks the Real Time Clock feature used by Pokemon.

The 8 GB allowance is also a bit much. Out of a 2 GB card, I'm using 650 MB for ROMs, sticking mostly to stuff I'd actually play.

 

Hey thanks for the replies! I do have a DS but I already have a fash cart for it. I'm looking for one to use only with my GBA.
What about a SuperCard? I can get the SD version from bamboo gaming for $37.
Do they have good rom support? The games I am looking at playing are pretty random. Broken Sword mostly and alot of rpg games.

 

Yup, Supercards have a problem with ram, but they are as cheap as dirt.

But the only slow down come in a few games like mario kart advance, tekken, etc.

 

I have not been able to get any cards above 2GB to run on my EZIV. The packaging meant 8Gbit or 1GByte, as it's been around a long time, and 1GB was considered huge at the time.

Who knows, maybe I'm wrong and SOME are supported above 2GB, but I can't be bothered to reformat my card and recopy everything over, so I won't be checking if the latest loader supports Fat32, and therefore some SDHC at best could work(as said, none of mine work)

Edit: definitely the EZIV though, it's a great card, I recommend the 'Mario' skin. I'm waiting for a SuperCard Lite to arrive so I can case mod it to a 'Phat' shell (replacement shells for M3 lol), and If it works good in my GBM, I'll let everyone know. (Created a post asking for comments, etc earlier)

 

Even so, GBA games aren't very big. The largest one is to my knowledge 32MB.

And with the proper math, i think you can store almost 65 32 MB games in one 2GB mini SD card.

Edit: DAMN, I didn't realize this was an old thread.