I think it's quite possible for it to look good if you're careful what you put together. My shower/tub fixtures and vanity faucet are all Delta but two different (similar) styles.

I had the same issue, we are just starting out master bath reno. All our fixtures (faucets, shower head, shower valves) are Moen "Voss" in brushed nickel, but the handheld is a Grohe on their Unica slide bar, also in brushed nickel. Go more for similar shape and finish and it will look great!

In my tub/shower, I have Grohe Arden for the faucet and spout (and vanity faucet) and Grohe Cosmopolitan for the handheld. All are chrome and they look fine together.

The key is using the same finish (all chrome, all brushed nickel). We've gone with all chrome except our vanity handles and trim ring on the shower recessed light which are brushed nickel. We have also tried to get everything in the same style with rounded/beaded profiles because that is what our vanity faucet has that we picked before we picked accessories such as towel holders.

It sounds like you want to have a custom shower system with both a hand shower and a showerhead. This is very do-able. Typically I would recommend you stick with the same brand, mainly because then you know the finish will match perfectly. Especially with finishes in the oil rubbed bronze category, you will find great differences between various manufacturers and it might look strange if the finish is not exactly the same. In the case of chrome finish, you may find there is almost no difference between companies. In that case there is no reason you couldn't have a hand shower made by one company, and a showerhead made by the other. You still need to do some other planning as to how your shower system will be configured. Perhaps this article we wrote about the topic will be of help. Delta Shower Systems

Example of a custom shower system with hand shower and showerhead