Peter....a Slightly non sequitur point....A turbine has a driven compressor....like a supercharger....a turbocharged (or supercharged) recip engine may well maintain constant power with altitude but who said that was the definition of turbocharged? Surely the definition is that the air charge is compressed...
A turbocharged engine's power also drops off as you climb. There are installations where the turbine operates at full power (i.e. with all exhaust) at sea level and there are installations where the turbine is regulated through a wastegate. The extreme variant is a turbonormalized engine where the turbine is controlled (automatically or manually) to never create more manifold pressure than at sea level without turbocharging.
A turbocharged engine is an engine where there is a compressor in the intake, increasing the manifold pressure over ambient pressure minus induction loss. If you look at a turbine, you will see that there are one or more compressors in front of the combustion chamber. The first turbines (WW II) shovelled all air into the combustion chamber, later designs used an ever growing bypass ratio.
Given that a turbine doesn't use its exhaust pressure to drive the compressor, one should probably say supercharged instead of turbocharged.
And a lot! Ours is only capable of burning 500lb of fuel per hour per engine
I feel better now about my 275lb/hr.
The power drops off as you climb.
And a lot! Ours is only capable of burning 500lb of fuel per hour per engine at 45,000ft while it can easily annihilate 1,500 at sea level :-)
A turbine (turboprop or turbojet) is normally aspirated. It's not turbocharged. The power drops off as you climb.
I am happy with my normally aspirated engine
A turbine is (as the name suggests) a combined turbocharger and combustion engine. One cannot be more turbocharged than in a turbine. How else would you get enough oxygen to burn those 120+ liters per hour? 
OK, so ignoring your list but making my own.
For long distance business type flying in Europe I want (in no particular order):
For bimbling:
So essentially as said by others, it depends.
As for a turbocharger, again depends. Only really important if you are going high or need to use high altitude airports. I am happy with my normally aspirated engine ;)
Things like transponders are nice, but again, are made valuable by the operating environment. The annual recertification costs for a transponder system in an aircraft is in the hundreds. if you need it, fine, but if your normal operating environment does not require it...
Bush flying in Canada is probably not going to get much safer by installing a transponder (but who knows, if you have to force-land in the bush, your last radar return might enable the rescue team to find you before the grizzly does).
But here in (south-western) Germany, a mid-air collision must be about the most probable cause of coming to grief for an aviator. We have had - and still have! - our fair share of those, the last one dating only a month ago (http://www.schwaebische.de/region/allgaeu/leutkirch/rund-um-leutkirchartikel,-Flugzeugkollision-bei-Kempten-Behoerde-bezeichnet-Zusammenstoesse-als-nicht-aussergewoehnlich-%2382-arid,5439556.html). So for me: No transponder, no fly.
And regarding the cost: Ask the wifes of those guys what they think about it. (Or as they keep repeating every year during our CRM course: "If you think, safety is expensive, try an accident instead!")
It depends on your average route, but going places is the way to fly for me.
VP & RG:
My plane is not available w/o both of it.
Turbo:
I added a turbo, to my aircraft last year and it changed my flying. I remember a pre-turbo take-off in Lausanne with 34C and DA of 4800ft, it was more creeping up than a climb as the terrain went up. Oxygen is a must and Mountain High is worth its money.
de-ice:
Something I miss badly, but too expensive to retrofit. It costs more than the value of my plane.
EFIS:
I'm fine with steam gauges, but if my HSI will stop working I will get an Aspen.
New points: FLARM:
I have to get a FLARM. I had 2 near misses with gliders (near Stuttgart) last month. They are so hard to spot.
AVTUR:
A non-AVGAS engine would be fab.
It is obviously important for the user of the aircraft to understand what they need, what they do not need, and what they can afford to install and maintain. There is no one right answer, as to how an aircraft should be equipped and configured. It should be appropriate to the intended application.
So rather than considering a wish list of possible configurations, it is more important to know what you must have to accomplish the task, and beyond that, what would be a nice to have.
After years of flying extremely well equipped aircraft, I opted for as simple as I could get, and could not be more happy that I did. I can rent or borrow better equipped for the few times need that capability, but it is surprisingly rare for me. But, I do not fly IFR, or routinely at high altitude. Obviously, if I did, my equipment needs would be different.
After hundreds of hours flying the Aztec and Cheyenne in actual icing conditions, I am convinced that there are very few singles which should be equipped or approved for continued flight in icing conditions. Those aircraft should be flown with a "stay out or get out" approach.
Things like transponders are nice, but again, are made valuable by the operating environment. The annual recertification costs for a transponder system in an aircraft is in the hundreds. if you need it, fine, but if your normal operating environment does not require it, and the airspace is not busy, their utility may not justify their cost and maintenance. I purposefully did not install the second transponder I have in the second plane I have.
I approved a turbocharger installation on a floatplane for a client, as he needed the power to be available for high altitude lake operation. The cost for that installation exceeded $50,000, and 93 pounds of useful load. He's happy with the plane, and it does what he wants, but carrying less, at a much greater cost.
For any aircraft for which water immersion is a possibility, the less avionics, the happier everyone will be. Many times we have pulled a fully IFR equipped floatplane from being upside down in the water. it's a quick way to trash tens of thousands of dollars in avionics, which probably were not need for water flying anyway!
All that extra stuff costs money, maintenance, and useful load. It's fine if you need it, but make sure it's worth it!
My minimum gotta haves: Four point harness, good headsets and an intercom, decent GPS, survival kit, and life jackets or suits for over water flying.
