Our Mimaki 3 year warranty ran out in the summer, after some research we decided to go with Atlantic Tech inks, and have not noticed any difference in quality / colour. Stafford is your man on here.
But as your machine is in warranty a would suggest you stay branded.
Are you using SS21 or SPC?
As soon as the warranty ran out on our Roland sp540v we switched to JETBEST inks.
That was more than 8 years ago.
There was no difference in the print, and we were still running the original heads until a few months ago, which is a pretty good run for a busy machine.
The only drawback is our machine doesn’t recognise the chip on the cartridge, so we just swap it for the old one when we change.