Really it depends on your needs and how much you wanna spend. Most people are going to say stay away from supercharged engines though.
An islandia would give you plenty of space but they are different than most jet boats. they are more like a deck boat. A speedster would be a smaller boat at 20 ft, so 7 to 8 people would be kinda cramped. A challenger 180 will be too small also. Either of the 23 ft boats in 08-09 would work good. The Speedster or Challenger.