The simple answer to this question of whether single particle is "better" than ensemble (bulk) particle analysis is... one needs to be specific about what they are looking to learn.

Single particle chemical analysis of aerosols is complementary to ensemble or bulk analysis of aerosol: each gives you a different kind of information.  

Single particle methods excel at describing the mixing state of the aerosol (do chemicals reside in the same or separate particles?) and can do a nice job in determinations of aerosol source contributions to an air mass, but tend to struggle with mass-based quantitation.  Single particle mass spectrometers produce large datasets in relatively short time frames, requiring data clustering methods (ART-2a, K-means, etc) to reduce the data to something more analytically manageable.  Microscopic single-particle techniques (when operated without computer automation) can have the opposite problem, where they can sometimes struggle to provide statistically-robust data due to high analytical costs per particle, but provide high resolution spatial information and now some even provide spatially-resolved spectroscopic information.  

Ensemble aerosol techniques provide strong mass-based quantitation of the aerosol population, which is valuable for many types of studies in which mass closure is important.  Since aerosol mass increases as the cube of the particle size, these measurements tend to emphasize the influence of larger particles on the sample, unless the technique explicitly size-segregates the sample.  Ensemble aerosol sampling, when performed at sufficiently high temporal resolution (e.g., real-time mass spectrometry), can be used to understand aerosol sources using a source-receptor data analysis tool -- Positive Matrix Factorization has been widely applied for this purpose in many studies for over a decade.  Bulk/ensemble analytical methods fail to describe the mixing state of the particle population, and sometimes can struggle with accounting for changes in number concentration of small particles, which do not constitute a large influence on the total aerosol mass, but can be important for cloud properties, for instance.  

Both types of information are valuable, but which one you require depends very heavily on the type of scientific question you plan to ask.  If you're looking for a study where both are used, I'd recommend the attached companion papers by Dall'Osto et al. and Decesari et al. where they use both techniques to characterize aerosol in the marine boundary layer.  There are a lot of examples of studies where it is stressed that one of the two approaches is more appropriate for a certain application, but without knowledge of your scientific question, this would be difficult to help you assess which would be more appropriate.

Article Primary and Secondary Marine Organic Aerosols over the North...

Article Nitrogenated and aliphatic organic vapors as possible driver...

This is a question that is often asked and Douglas gave a great answer.

There are also a few studies where single particle mass spectrometer data has been converted to mass concentration with a good degree of success. See for example the Paris papers by Healy et al. 

There are also several efforts to compare single particle mass spectrometry and  electron microscopy - see Arndt et al. and also a paper quoted in this article by Roy Harrison and co-workers.

Article Sources and mixing state of size-resolved elemental carbon p...

Article Quantitative determination of carbonaceous particle mixing s...

Article Scanning electron microscopy-energy dispersive X-ray spectro...

I am extremely happy that you guys ,Abhishek, Douglas and John, answered so nicely. Thank you !!!!

I will read all the suggested papers than i will come back with my quarries thank you !!!!!!!