Rio M and 6.5 is my suggestion for something you can start out on easily, and then get a larger rig or 2, but keep the 6.5 m2 for your 18+ knot days.
The Severne NCX is good, I've sailed them.
If you have a Sailworks dealer nearby or are in the USA, the Sailworks Retro 6.5 m2 would be my first
suggestion. Cost a little more, but the after sales service and the overall quality are well worth a bit more.