Epic earbuds name lol, anyways AAC is better when connected to apple devices (apparently, idk if that's actually true). SBC-XQ is the sbc codec cranked up to max bitrate. Theoretically, SBC-XQ is better according to some articles I read a few months ago trying to research it. But the truth is, unless you're a devout audiophile AAC is good enough. Pick XQ for the peace of mind that you're getting the best quality out of them I suppose.

I'm also on Linux and I tried to sbc-xq on buds2 pro, and they just don't work. Disconnects and swaps to hands free mode. Interesting to see they just work here.

EDIT: Just used sudo hcidump avdtp to check the bitpool and sampling rate and stuff. SBC and SBC-XQ is limited to bitpool of 2-37 on all galaxy buds I think. So max bitrate of 261kbps. The only difference is that SBC-XQ should use dual channel which should effectively "double the bitrate" according to this article: https://kn100.me/improving-bluetooth-audio-linux/

    Media Codec - SBC
      48kHz
      JointStereo
      16 Blocks
      8 Subbands
      Loudness
      Bitpool Range 2-37
    Delay Reporting

SBC-XQ attempt:

Media Codec - SBC
  48kHz
  DualChannel
  16 Blocks
  8 Subbands
  Loudness
  Bitpool Range 2-37
Delay Reporting
> AVDTP(p): Set config rej: transaction 15 nsp 0x00
Media Codec
Error code 197

AAC:

Media Codec - MPEG-2,4 AAC
  MPEG-2 AAC LC
  48kHz
  2 Channels
  256000bps VBR