Sailing experience with scenery, meeting people and price
Most definitely Sail Croatia. All the tour companies (with a backpacker / student audience) use one sailing main company, and I believe Sail Croatia has the lowest profit margin (its cheaper).
I went with them in September last year and was very happy with the crew and the quality of the food. The itineraries are mostly identical, but may be worth looking into the inter-island transfers if you want to go somewhere in particular.
Have a great time... its an amazing stretch of coastline! about 10 years ago