Most stable chair conformation
The lowest energy conformer for a cyclohexane ring with multiple substituents will be the one in which the largest group occupies an equatorial position. 

Steric parameters are tabulated in many organic chemistry textbooks, the most common of which is the A-value. The A-value represents the difference in energy (ΔG) between a group being axial/equatorial on a cyclohexane ring, thus, as a group gets bigger, its A-value increases, reflecting the increasingly high energy needed to flip the ring. 

Bulky substituents such as tert-butyl are often said to "lock the conformation", that is, with a tert-butyl group on a ring, the energy to flip is sufficiently high that ring is "locked" in the conformation with the tert-butyl group equatorial.

In your example, building a simple model with a kit will show you that having the iso-propyl group axial isn't terribly favourable (interestingly the iso-propyl group has a similar A-value to ethyl, due to the ability of the group to rotate, avoiding having a methyl group pointing into the ring).

I ran a few simple calculations (molecular mechanics followed by DFT optimisation - gas phase) on the axial and equatorial conformations, which showed that the two conformations are separated by around 3.4 kcal/mol.  The minimum energy conformation of your example is shown below: