I'd say choice between a turboprop or a reciprocating engine may depend on your power needs, and the type of 'mission' the engine/aircraft will endure.
Turbines and Turboprops, even with its advantage of weight to power ratio, are not that good regarding SFC, if you check this in www-jet-engine.net civil turboshaft-turboprop specifications, most of it have an SFC in the range of 600 lb/shp/hr, or more.
The Harry Ricardo and Roy Fedden Single Sleeve-Valve distribution Aircraft Engines provided the best ever SFC in a gasoline aircraft engine: 0.42 lb/BHP/hr in an Hercules Centaurus, 3272 cu. in., with a weight of 2695 lb, for a power of 3150 HP. Even more impressive results were obtained with an Open-Sleeve, acting as an annular piston with 10% of piston area, transmitting 3% of power, in an experimental 2-Stroke Compression Ignition Engine by Harry Ricardo. No Sleeve-Valve engine is produced today, but new replacement sleeves for old engines are still manufactured, they said this in AEHS, but I failed in locating the seller of Sleeves for old SSV engines.
Best SFC ever seems being obtained in an open-sleeve valve, two-stroke, compression ignition engine, by Harry Ricardo, at 0.34 lb/HP/hr ('The high speed internal combustion engine', 1968 ed)
A poppet valve engine of the times of Bristol Hercules, the Wright R-3350, 2907 lb weight, also air-cooled, with same number of 18 cylinders; 3348 cu. in.; 2800 HP, used 0.72 lb/HP/hr, but this was greatly improved in the Turbo-Compound units, that added 500 lb weight more.
The Sleeve-Valve engines were known for its reliability and low wear, the no-lubrication zones of TDC and BDC are wiped out by the continuous sleeve movement, the Bristol Hercules had a TBO of 3000 hr or more, for 2000 hr TBO in the Wright cited (data in AEHS and other sources). Sleeve-valve engines, having no hot spots in combustion chamber, can work on low octane fuel at higher Compression Ratios than poppet valve engines.
The experimental Single-Cylinder, 500 cc, Sleeve-Valve gasoline unit built by Mike Hewland for Automobile use was reported having an SFC of 0.45 lb/HP/hr in the racing version, and 0.39 lb/HP/hr in the economical version (Car&Driver, July 1974), working even with creosote.
A Rolls-Royce Turboprop, the Dart RDa 10.1 series, with 2915 HP and a weight of 1207 lb, consumed 0.550 lb/HP/hr.
You can't find today reciprocating engines in power ranges above a certain limit.
The Wankel Rotary Combustion Engine, that had extensive development for aviation and other uses by Curtiss-Wright, John Deere, NASA, NSU-Citroën, Sachs, Aixro, Rolls-Royce, Mazda, had an SFC of 0.46 lb/HP/hr with a weight of around 210 lb for a power output of some 120 HP, street car version, as reported in an early Mazda NA Wankel Engine, 2 Rotor, liquid cooled, a Wankel will work with no toil with unleaded gasolines around 80-90 ON, also with 10% Gasohol, that provides lower SFC and reduced operation temperatures and thermal load, some added lubricating oil to fuel and working chambers is always used in Wankels, no need of changing lubricating oil.
A major breakthrough was achieved recently in the Florida University, where they proved that adding: 'Heat Pipes', for cooling the housing and side plates of a formerly air-cooled housing charge cooled rotor UAV UEL engine reduced maximum temperature to a mere 129º C, and maximum temperature difference between engine parts to 18º C, the use of: 'Heat Pipes' for cooling Wankel RCEs, as it were used in satellites, may be an enormous step forward in Rotary Combustion Engines, as it eliminates most if not all thermal dilatation differences between parts of engine, making design and construction much easier, also improving reliability, from a reduced wear, enhancing power, reducing emissions and boosting fuel economy. Who could ask for anything more?
Standards for reciprocating aviation engines were around 1 kg/HP weight to power ratio, and 250 gr/HP/hr SFC.
No Wankel Rotary Combustion Engine seems having obtained yet an FAA certification for regular general aviation use, even when it are considered safer than reciprocating engines, Wankel RCEs failures tend not being total and instant as in reciprocating engines, a residual temporary lower power working would allow for more safe landing opportunities, this safety concern was approached by something close to the basic concepts in an hybrid car by Axteraerospace.com
This one is an example of Turbine for General Aviation build in Argentina, basic arrangement reminds the first Turbine by Hans Joachim Pabst von Ohain