It depends upon the property what are you looking for?

I could say, Yes, it has a major role played by the aspect ratio of 1D magnetic nanostructures in the reversal magnetization process.

It depends upon the property what are you looking for?

I could say, Yes, it has a major role played by the aspect ratio of 1D magnetic nanostructures in the reversal magnetization process.

For low cost flexible electronics.

good electrical conductivity, if the material itself is conductor

Uniform NWs are gives better conductivity and thereby improve the performance of devices. In non uniform NWs there is loss of charge transfer due to scattering and other complicated process involve in transportation of charge carriers.  

For optoelectronic applications, uniform size distribution will give you narrower emission line width (more monochrmoatic).

Yes the uniform nanowires effect on thermal, mechanical, rheological, physical, electrical, and surface properties.The heat and charge flow, viscosity and Young modulus, and hardness and brightness depends on the structure arrangment.

best wishes

With uniform shapes and sizes of nanostructures one gets more clear and more reproducible results, e.g. spectra with reduced inhomogeneous broadening for ensemble measurements. Different spectral features are then easier to analyze and it is more straightforward understand they origin. This is a general remark since this applies to nanowires, quantum dots, etc.  This is also one of the reasons why many times we ultimately aim at the single nanostructure measurement rather than ensemble studies.

Regarding the second question: aspect ratio (height/diameter) would be important only for short nanowires, but then you probably should call them nanorods. On the other hand typically even for "long" nanowires (e.g. 1 micron length and more)  nanowire properties depend heavily on the diameter, with 5 nm and 50 nm diameter nanowire showing very different spectral behavior.

good electrical, thermal and mechanical prperties

please read my article with title of "Electrochemical pore filling strategy for controlled growth of magnetic and metallic nanowire arrays with large area uniformity" to get your answer.

http://iopscience.iop.org/article/10.1088/0957-4484/27/27/275605

It depends upon the property what are you looking for.

A uniform nanowire can play a very important role in the process of reversal magnetization with respect to the aspect ratio of 1D magnetic nanostructures 

If you talk about the property of nanowire, the uniformity may not very critical. Because such properties were determined by the quality of the nanowire. However, the uniformity is usually used to describe the nanowire arrays synthesized on the substrate. It is very important to the stability and performance when you apply it for the device.

Thanks everyone for the enlightenment ! Cheers