Unlike block ciphers, stream ciphers do not have a standard model. A variety of structures are followed in stream cipher design. The stream cipher project of ECRYPT: eSTREAM aims to identify new stream ciphers that might become suitable for widespread adoption. 34 submissions are made in this on going project, based not only on conventional designs but also on some novel ideas. In this paper a comparative study of these submissions is made with respect to the design structures they have used. Our work aims at having a review of different design philosophies which were used in past and those which are adopted in these submissions. This study of the proposed ciphers also gives an insight into the recent trends in the design of stream ciphers.