I'm a professional plumber, and would like to think I have some insight in my last 25 plus years. However there are always people who will disagree, so you can either take what I have to say to heart, or leave it.

To a point spending money does get you a better quality fixture. Number one don't buy from big box stores, stuff is made cheaper, and is not the same as a supplier model. That's why it's cheaper...

Now that being said, there is a point where you are just spending money to spend it, and there is no return of value. I would also caution you to remember that most sales people (even at a supply house if they actually work sales and not counter help) usually make a commission. It's in their best interest to upsell you. There are so many brands and variables that it is damn near impossible for me to point you in the right direction with the information I have. One example is that I would go with any ghroe shower valve over any hansghroe valve. Based on quality, and cost and serviceability of the valves. For the most part I would actually recommend a delta multichoice rough valve and 3-6 function diverter over the ghroe for the same reason. But this all depends on a ton of things, like trim style and finish you are going for, and actual functions of the shower, just to give you a couple examples.