Which Flash Cart Should I Get?

It's often hard to tell which flash carts have which features.
How do you know if a feature really is unique, or if all carts have it?
Which carts still get updates to play my new ROM/game dumps?
Which are the barebones carts, and which are the feature-rich ones?​

A public poll was held and only the top-ranking carts are included here.

If you don't understand a term or concept, check out the DS/DSi/3DS "hacking" F.A.Q.
If your focus is GBA games, check out this guide instead.
Battery life may also be a concern. This thread has more information.



Of note is that the DSTwo is the ONLY flash cart that has NEVER needed a new hardware revision/model in order to work after a DSi/3DS update. This means that with other flash carts you may need to buy a new one after an update, but so far that has never happened with the DSTwo. Because of this, the DSTwo is considered the safest flash cart purchase.


Seeing as there's many clones and similar-named carts out there,
here's links to the official websites so you can visually match it.

• R4 (Site defunct, use it only as a reference. Use Wood from filetrip.)
• Acekard 2.i / 2i (Use the AKAIO download on that site, or from here.)
• R4i Gold / R4i DSN
• Supercard DSTwo. (Get the EoS/Software and such from the official site there.)

Chart Explanation/Key

Warning: Spoilers inside!

"The cart I want isn't listed here!"
"There's not much here, it must be outdated."
"I'm not seeing (Cart X) and it was good, so you must be wrong."
"This cart gave me two updates so it's a good one!"
etc.

• The chart used to be bigger with entries like the Ak2i, M3i Zero, DSonei, EZ-Flash Vi, iEvolution, etc... but those carts stopped getting updates/support, so they were dropped off the list. Updates not only mean the ability to play new games, but also the ability to work at all on a DSi/3DS (which have anti-flashcart updates themselves). The list is so small nowadays because the DS is dead, so most of the good teams have simply discontinued their products.
  
  As far as all the fakes and clones... these are Chinese aftermarket goods, so there's a lot more bad-quality products out there than good ones. Especially when it comes to any cart with "R4" in the name, 99% of those are fakes or knockoffs because the original R4 team only made "R4". Any "R4i", "R4 SDHC", or anything else like that was not made by them (and a large majority of them are badly-supported carts). These carts will often give two or three updates, then drop off the face of the planet.
  
  While there are some flash carts that actually try their best to give support and updates (you'll notice an R4-named cart IS in the list), the majority out there will drop support quickly in order to get you to buy a second cart, then a third, then a fourth...
  
  http://gbatemp.net/threads/update-o...d-v2-0-using-akaio-updated-to-3ds-4-3.342339/
  http://gbatemp.net/threads/identifying-flashcart-fixing-one-for-my-nephew.341230/
  http://gbatemp.net/threads/r4itt-purple-new-sticker-problem-about-adding-games.343271/
  http://gbatemp.net/threads/r4i-sdhc-help.342623/
  http://gbatemp.net/threads/r4itt.342556/
  http://gbatemp.net/threads/software-for-green-r4i-card.316171/
  
  Check out those threads, people bought carts from teams that didn't give support, and so were left with carts that wouldn't play new games, or even work at all on their DSi/3DS. This is why it's so important to pick a product from a site/team that actually attempts to give more than one or two updates, and unfortunately that list has shrunk as teams simply stopped and left.

Changelog

Warning: Spoilers inside!

8/21/2013 - Updated the explanation chart to account for 3DS ROMs being playable. Actual cart chart update pending correct info.
4/23/2013 - Added r4idsn.com split site, fixed a bbcode typo that was cutting a bunch of stuff off.
4/22/2013 - Removed "Slow Motion" since it's part of the real-time menu function. Added a section on bootloader updates without new hardware, as that's become a real strong point of the DSTwo, and a real weak point of all the other flash carts. Also edited a little wording on the explanation chart while updating it as well.
4/20/2013 - Huge update, condensed some info, rearranged some, added a large note on why people shouldn't buy clones.
3/30/2013 - Changed example/review category link to the flash cart demonstration thread.
2/14/2013 - AK2i's dead, replaced it with the 2.1 for people that want SDHC support and such on a DS/Lite.
12/15/2012 - Changed the AK2i to "Partial" in the DSi column since 1.4.5 came out a few days ago and still no sign of the team. Also change the R4i Gold model's real-time column to "yes", since Wood's RTS feature is coming out. Re-arranged things too, to flow easier.
11/3/2012 - Updated the AK2i as "Partial", since it's been months slow in updating for ages.
7/20/2012 - Fixed the images.
6/08/2012 - Added links to the official sites for clarification.
4/29/2011 - Fixed the merged cells for the 2.1 and 2i, whoops.
4/9/2012 - Added link to the GBA game guide.
3/22/2012 - Updated chart with the results of a new poll. Also modified some of the wording in the explanation to expand upon the carts listed.
5/19/2011 - Fixed R4iDSN bootloader update column, whoops.
5/7/2011 - Added a note on why this doesn't list all carts.
4/25/2011 - Fixed erroneously listing the Cyclo carts as having Auto AP Bypass.
4/25/2011 - Fixed a typo, properly hosted pictures on gbatemp.
4/24/2011 - Initial version.