I have both CIMB CR and UOB VOX.
The best one is PBB VS but I'm short of 10k of annual salary to qualify for it, so I just stick to these two for now.

My summary as below:
i) CIMB CR is a free for life card while UOB VOX is not, you will need to spend at least once per month (no minimum amount) to avoid RM 6.00 monthly charges.
ii) CIMB CR has no minimum amount for online transactions in order to be eligible for cash back but VOX requires you to spend at least RM 50 per transaction to be eligible for cash back.
iii) CIMB CR's maximum cash back for online transactions is only RM 30 (that means max spending for online transactions is RM 600) while VOX can be fully maximized at RM 50 (for RM 1k of spending).
iv) CIMB CR's has a fixed date of cash back crediting while UOB VOX is by 30th of following month, usually out around 20s of the month.
v) CIMB CR has cross borders charges (read here) while VOX doesn't have.
vi) CIMB CR's maximum cash back for online transactions is only 5% while UOB VOX is 5.3% (5% - online transactions + 0.3% retail transactions).
vii) CIMB CR doesn't give cash back for flight tickets while UOB VOX gives.
viii) CIMB CR doesn't give cash back for UOBPayOnline transactions while UOB gives (refer to first post of this thread).

For utilities, please refer to point (viii) and you definitely need UOB VOX.

In conclusion, apply both.