In the 6 seat world I've flown 55 & 58 Barons, Seneca 1,2 & 3, C310R, Aerostar & Aztecs. They each have pros & cons.
B55: Nice to fly. Limited space for rear pax. Have to clamber to get in the back. Very limited baggage space if 6 POB. Instrument Panel is very cramped thanks to the space used by the centre control/throttle mount. Narrow cabin
B58: Nice to fly. More room (of course). The rear doors are a godsend. Instrument Panel is very cramped in the earlier models ie before the control column change thanks to the space used by the centre control/throttle mount and the stupid multi section panel. Newer Post change Barons are much better for instrument panel room. Narrow cabin. An older pressurised model is available. Still being manufactured.
Seneca: Rear door! More useable panel space than older Baron. Wider cabin than Baron. Can have all forward facing seats or club. I think the Baron is nicer to fly, though. Seneca 1 is slow & has minimal assy performance. The rest are turbocharged so will incur some maintenance $. Still manufactured as the Seneca V.
C310: Two steps to get onto the wing to enter which can be awkward for less able people. More room than a B58. Wider cabin. The R model has heaps of baggage space compared to a Baron. That long nose + aft + wing lockers. Have to clamber to get to the rear seats. Why Cessna didn't make a proper door when they chose to enlarge the cargo door from early C310s is beyond me.
Aerostar: Fast. Wider cabin than Baron. Everyone sits upright, unlike Baron, C310 & Seneca where the rear seats have your bum only a couple of inches above the floor. Not for shorter runways. Nice to fly. Have to move the pilot seat forward, and stagger R2 to get the pax in. Normally aspirated, turbo, and turbo/pressurised versions available
Aztec: Slowest of the lot (apart from Seneca 1) and thirsty. Easy to fly with quite good short runway performance (same aerofoil section as a Piper Cub, so no great surprise there re speed & runway performance). No rear door to load aft pax so clamber again. Proper rear seats unlike the bum-near-floor types above. Good cargo space. Excellent payload/range trade off - one of the few aircraft types I know that can take full fuel, an adult bum on every seat, and still have some weight capacity left over for bags. All the previously mentioned aircraft have to limit fuel to fit 6 adults, sometimes quite restrictively.
Other types you could consider but I've not flown:
Cessna 340
Cessna 303
Aerocommander
As a rule of thumb, for any reasonable distance flying with a load, most GA types can be regards has having 2 seats fewer than what the manufacturer stuffs in them.
If you really need to take 6 people regularly to go places then you might need to consider 8 seat twins eg Navajo and the like.
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Later...
Forgot to mention the C336/337. No worries about asymmetric handling problems. Unless you have the cargo pod no baggage room with six people. Cabin room is somewhat similar to a C206 without the cargo area.
Last edited by Tinstaafl; 12th Feb 2015 at 03:19.