I stayed at Istana, Mutiara, Marriot, Renaissance before, All hotels are 5 stars.
Marriot is in superb location. Bujit Bintang is just at doorstep but breakfast sucks
Istana is the cheapest among these hotels. Value for price.
If you are looking at Budget hotel, Istana would be good. Need to walk 8mins to Bukit Bintang.
But I like Renaissance hotel cos its a relaxing hotel and the pool is good. Me went KL to relax, not really for shopping. Hence, really like Renaissance.