Having owned and raced the H16, TheMightyHobie18 and H20, I think the 18 is the most versatile. Easiest to de-power (only model with roller furling jib standard). Will handle you, your buddy and your wife/gf's when you want. A very rugged boat. Faster than the 16 on all points, but downwind a bit of a pig. And of the three the most comfortable (safe) "feeling" when solo.

All boats can be rigged singlehanded, you'll want/need a mechanical advantage for the 18's mast.

Would you launch from a ramp at the lake?

Check around on the HCA site and Hobie Cat community forum. There are several TheMightyHobie18 sailors in your area.