How much games are you trying to play? a game takes about 5 minutes to customize, and you can automate the process so it's about 2 minutes.
Injection has a few things better than GBARunner2:
Runs perfectly
GBA Games appear in the home menu
You can add sleep and hard-reset patches
GBARunner2, while being simple drag and drop and pretty good emulation,
can corrupt your SD Card (if you enable saving)
and isn't as accurate as the injects.
Although if you still insist on easy play of GBA Games you have 2 options:
Use TWiLightMenu++ for GBARunner2
or (If you have a NEW 3ds) use mGBA's latest builds.
OLD 3DS Systems can't emulate GBA Well.
If you want to inject games go to this tool:
It can inject way more than GBA.
https://gbatemp.net/threads/discussion-new-super-ultimate-injector-nsui.500376/