I agree with Jon Isaacs. There’s no single instrument. The difference in apparent size is to big.
NGC 4755 (the Jewel Box) is great in the KOWA Highlander Prominar at 32x with it supersharp center and great presentation of the different colors in this tiny cluster.
The Hyades cluster (Melotte 25) looks great in my Fujinon 7x50.
As I like observing open clusters the answer to your question is: see my signature
I try to “zoom out” to a certain extend to have an overview and compare different stars within the cluster to see where they fit in the H-R diagram.
To be a able to observe a wide range of cluster without burning your wallet follow Astro-Master’s advice