DS have bad rep with the mk3 RS, whether that’s justified is yet to be seen but a certain couple of utubers stained there reputation to be honest.
Your most common answer on here be MSD multimaps which could suit you well as start on MSD380 and then move to 400/420 as you upgrade parts.
the other tuner will be sabre for custom tune.
outside of that there many to choose from, I have revo 1 and have no complaints but quick straight line car the RS will never be unless you spend 1000’s.