GrafX2[0] VS Aseprite[1]

  Licensing

GrafX2: GNU GPL v2 -- FREE & open-source, true FOSS software.[2]

Aseprite: EULA (since v1.1.7) -- open-source for personal use only, not true FOSS software.[3]

  Programming

GrafX2: main lang -- C ; GUI -- SDL1.x ; addons lang -- Lua 5.x.[2]

Aseprite: main lang -- C++ ; GUI -- Qt5.x ; addons lang -- JavaScript.[3]

  Supported platforms

GrafX2: Android, AmigaOS, AROS, Atari, BeOS, *BSD, Canoo, GP2X, Haiku, Linux, macOS/Mac OS X, MorphOS, Windows, Syllable, and much more.[4,5]

Aseprite: Linux, macOS/OS X, Windows.[6]

  Performance/Memory usage

GrafX2: ~ 50-200 Mb RAM

Aseprite: ~ 450-600 Mb RAM

[0] http://grafx2.tk

[1] http://aseprite.org

[2] https://gitlab.com/grafx2/grafx2

[3] https://github.com/aseprite/aseprite

[4] http://pulkomandy.tk/projects/GrafX2/downloads

[5] http://grafx2.chez.com/index.php?static3/downloads

[6] https://www.aseprite.org/trial/

I trialed several different pixel art tools and really like Aseprite so I purchased a license for the full edition.

I was asking more of a feature comparison of why one would be better in terms of actually creating pixel art and animations, not a licensing and memory consumption comparison.

You should maybe answer the actual question asked by parent instead.