6 adults
I too have flown many of the types mentioned.
Love the 310R and B58, both very versatile, so many pros and cons.
Seneca II I flew was a good performer, great pac appeal in the back but not as robust as the Cessna or Beech.
As mentioned forget about 6 adults in the above.
The Aerocommander Shrike 500S is the beast for you! Great aircraft, not as fast but can carry 6 plus gear. Also you can get the Renaissance version that has been 'zero' timed.
It's all money, it really depends on your budget. Also if you plan on keeping it as a private you or putting it out to work a little. Either way look at the sums, hiring whilst expensive may just work out cheaper!
Have fun, I know I did!