I recommend the pusher configuration, placing the propeller behind the fuselage or wing, for traditional aircraft (those that create lift using a wing). In lieu of tiltrotors, helicopters, and/or quadcopters; I recommend thrust vectoring nozzles. Thrust vectoring nozzles create lift by redirecting the flow from a ducted propeller (a.k.a. axial flow fan), they can be fixed or adjustable. To create static pressure, I recommend placing a diffuser behind a ducted propeller. The use of a ducted fan in combination with a diffuser is a replacement for an axial flow compressor. An axial flow compressor utilizes a rotor and stator to increase static pressure (the combination of a rotor and stator is called a stage). Velocity is constant through an axial flow compressor, this requires area to decrease. The diffuser creates static pressure by decreasing velocity and increasing area. The combination of a ducted fan and diffuser has many benefits over an axial flow compressor; higher thrust-to-weight ratio, higher efficiency, less cost to manufacture, cheaper to maintain. However, since axial flow compressors typically utilize multiple stages, the combination of a ducted fan and diffuser will not create as high of a pressure ratio as a typical axial flow compressor. Axial flow compressors require tight tip clearances. Ducted fans do not require tight tip clearances, regardless if they are used by themselves, with diffusers, or with thrust vectoring nozzles. Below are pictures of these configurations:
Sweeping the airfoils is recommended over sweeping the blade. You should only use sweep when the vehicle velocity is greater than Mach .5. You can not tell visually if the airfoils are swept or not. Many propeller manufacturers create the illusion of sweep by manipulating the chord distribution (one such example is scimitar blades). Many propeller manufactures also tout the virtues of sweep for low speed aircraft, don't let them fool you.
Below are pictures showing the same blade with two different sweep methods. They both perform the same aerodynamically. However, the swept blade configuration may cause structural problems. Therefore, using the swept airfoil method is always advised.
I recommend the following software for PROP_DESIGN users:
The following software is worth checking out as well: