Bonus share is a way to increase the equity base of any company. Investing in any stock with a sole intention to benefit from bonus issue is a wrong concept as price correction occurs later. By no means, it should be considered as a parameter to judge the future prospect of any company.
There are several factors that should be kept in mind before investing. It is an additional benefit that the company that you have chosen is also giving bonus shares. But never invest with this sole reason.