I have many different deities in my alter. Moreover, since i am from a very mixed background , i was brought up believing in all forms. However, the main deity in my alter is mariamman. Guess she is the form my parents believe. In my opinion, i think that god was given such many forms by humans so that the mind is able to connect and focus in the divine in the way it desires. If we can see,the various deities have various emotions or concepts attached. For example, ganesh - symbolises overcoming obstacles, letchmi- wealth , saraswathi - purity, education, concentration , hanuman- cotrol of the monkey mind and durga - strength and love.Therefore, usually the emotions we seek or possess will manifest in form we choose to focus our prayers on. But what matters is not who we worship but the motive behind our prayers. There could be many forms of him, but all forms are HIS . The important message here is forms of god are created to enable us to control our mind n heart and use them to focus on the ultimate. And prayers should always be performed with pure heart n soul.
* One need not seek for divinity, he has been always within him.