I’d go with rasterlink 6 if this is your only printer. It does what it needs to and is literally made for mimaki. It’s cheap and does what it needs to.
If you plan on printing a lot, I’d highly recommend at least getting a trial of onyx at some point, it’s much easier to use, very visually friendly and has loads more extra options compared to a very basic rasterlink. We’ve had it a year and it’s already saved us countless hours. Plus if you ever want to start making your own profiles etc that’s also available to you.
(I even switched my CJV-30 from RL to onyx at the additional licence cost as its soooo much better). My two cents!