Vk singhania vs tn manoharan for ipcc taxation?

You have not mentioned about which level you are in...? Inter or Final.

Anyway whichever Level you are, If you want Indepth Knowledge in course of your Studies itself Go for V K S & if you want to study from the Perspective of Passing the exams First then Go for T N M. This book will give you Knowledge & Information Good enough to clear your Exams in a very Nice & confiident way

VK Singhania is for indepth general study of Income Tax.

TN Manoharan is specifically for CA exams.

But, if you are giving exams in May 2015, then the time to study from VK Singhania and TN Manoharan is long gone. Both books have 1000+ pages. And you have other subjects also to cover.

You need a short and crisp study material.

Go for the latest Practice Manual + RTP for May 2015+MTP for May 2015. 

This will suffice for IPCC exam.

Go for T N Manoharan sir's book. I myself have followed in IPCC.

Its a very student friendly book. On the other hand, V. K. S. is an advanced level tax book for the ones who want to get a basic understanding of income tax.