Which cement is better for a slab between Bharathi and Ultratech?

Prima facie, any of the cement brands mentioned by you is quite acceptablefor the RCC slab you have in mind.

Preference shall be given to any of the two brands which offers you:

1.Competetive pricing

2.Better technical support such as test report, mix design, handling queries etc.

3.Availability of the RMC plant with the provision of concrete pump ( for larger quantities of the concrete)

4.Ease of queries resolution

5.Overall approachability

Based on the comfort in these five aspects you can consider which brand to be opted.

Hope you have got the basic idea now.