Right. So, really, DS enjoys most of the positives of the GBA, while having its own awesomeness.  IMO, DS wins by a mile, largely because of this fact.  

I played the GBA in high school, and it was one of the systems that really got me into gaming, so I'm a bit biased. I also never owned a Super Nintendo, and so this system was a treasure trove of amazing experiences. Stuff like Fire Emblem, Golden Sun, Final Fantasy Tactics, and the Dragonball Z Legacy of Goku games really made this one of my favorite platforms ever.

The DS was also great, but unfortunately its best years were while I was in college and beginning my career, and so it didn't get as much love as it should have. Had some nice memories on it, but honestly I probably used the GBC backwards compatibility just as much as I played actual DS games...so that's another point for the GBA there.

DS for me. The 2 screens just made for an overall better experience, and it's also the system that everyone around me had, so it was great for multiplayer games like Mario Kart DS. And I didn't need that stupid cable either, so 4 or 5 people could play at once. Honestly, it felt like a huge step forward in a way that the GBA just didn't.

Also, there's the sheer volume of that game library. To this day, I still have a huge backlog of DS games. This system seriously has something for everyone.

Can't comment on them since I haven't played either much, however I will say that it's actually kind of surprising how huge DS's library of acclaimed games is compared to GBA.

DS, but for a different reason than most.
The GBA arguably has a slightly better library for me.
ALL them SNES ports and sucessirs are just wonderful, and arguably beats out the ds's own offerings of the same type. Perfected 2d beats rudimentary 3d. (Aka SNES better thann n64)

That being said, the DS is no slouch. Pokemon was in it's absolute peak on the DS in opinion. Days of ruin is arguably the best AW title.

But all in all what matters in the BC. Gb and GBC BC does NOTHING to me. Pokemon? Heh, rather play let's go over RBY. Or more likely FRLG.

So the DS just dies everything GBA can but also more.

GBA SP is the best handheld of all time.

Since I love Point'nClick games, Visual Novels and anything similar with a nice story and/or good puzzles: the DS hands down.

DS:

• 4 awesome Professor Layton games
• 6 Ace Attorney games (AAI2 needed a translation patch)
• 4 CING games (Hotel Dusk, Last Window, Another Code, Again)
• Ghost Trick
• Broken Sword: Director's Cut
• Captain Morgane
• Flower Sun and Rain
• Secret Files 1 + 2
• Runaway 1 - 3
• Scribblenauts + Super Scribblenauts
• So Blonde: Back to the Island
• Syberia
• Time Hollow
• 999: Nine Hours, Nine Persons, Nine Doors
• some Nancy Drew games
• some Sherlock Holmes games

Zelda Spirit Tracks and Phantom Hourglass > Minish Cap (even if PH does so only barely)
Mario Kart DS > Super Circuit
Mario Party DS > Mario Party Advance

GBA doesn’t have a real Mario platformer of it’s own and DS had Professor Layton. I admit I stupidly missed Metroid and Fire Emblem, which were excellent, on GBA but that was because I had already given up on GBA (and GC) at that point.

DS was better.

If however you’re including the many ports on GBA it makes a much stronger case because then you’ll have to consider A Link to the Past, Yoshi’s Island and Super Mario Bros. 3. Is DS still better then? Not sure.

3DS and GameBoy beat both though, no contest there.

This ^

I have the Game Boy Player and Super Game Boy for those. Actually, I played my GBA games mostly on TV, curiously enough

DS - and it's not even close.

(Note, I'm an oldtime gamer, I played all of Nintendo's handhelds extensively, and among the first games I ever imported was the English version of Final Fantasy Legend, the very first handheld RPG - GB didn't require a fire converter).

GBA was a bit crap, to be honest; it felt a little like "What if Nintendo didn't release the SNES until 1995?" rather than an adequate update. If you thought getting the right angle on original 3DS was bad, try getting the right angle of a lightbulb onto the GBA screen... especially with games like Circle of the Moon. I think people voting for the GBA are forgetting this frustration. GBA STILL needed you to replace the batteries!

GBA SP was a massive improvement, but the screen was still dim. Again, lighting was a big factor, as it had the opposite issue of the original GBA: if it were played in a sunlit room, the screen could not be seen. On the plus side, it actually had a rechargeable battery built in, although it was only about 5-8 hours despite being a fairly weak handheld... also you had to charge it for 3-5 hours (usually overnight) in order to get it up to the maximum; usually playing involved having it plugged into the wall. Last issue, the GBA SP looked like a baby DS, it was very small.

While DS wasn't the most aesthetically pleasing console, its screen was significantly better than the GBA, and it was substantially more powerful as a console with a significantly longer battery life of 2-4X the GBA. On the software side, it offered a much wider variety of games and was capable of polygonal graphics - launching with Super Mario 64 as a port, which was fairly fantastic at the time.

While DS Lite didn't have the same power-awe as the original DS, its screen was even better. The battery life was over 20 hours, the screen brightness had a wide range (brighter than the DS, you could light up a small room with it). It was sleek, the most attractive handheld gaming device of its time (arguably ever, though I'd be more inclined to argue the Switch in handheld mode). You might say it was liteyears ahead of any GBA model.