Non-saxophone players look away now ...
I believe that a good setup is one that allows me to feel comfortable and makes me want to play. If I feel relaxed and motivated then my own natural voice will come out, regardless of what gear I'm playing on. There's always a balance involved, but if it comes down to the feel I want versus the sound I want then I'll always prioritise the feel and then trust the sound to develop over time. If I'm having to force it then it's always going to sound ... well, forced!
I'm mainly a tenor sax player and my weapon of choice is a P. Mauriat PMXT-66R. It's a well built, chunky horn and I love how solid it feels under my fingers. I've also customised the palm key positioning and venting a little, tightened up the action and fashioned a bespoke high F# key raiser to allow for ease of access throughout the altissimo register as well as a bunch of cool effects. I play on my own custom Syos mouthpiece and I use Legere Signature reeds. I'm also a big fan of tone enhancers and I use a West Coast Sax Buzz Screw, a Corry Bros Tone Tablet and a Gold Plated Reed Geek Klangbogen. Despite what some people might tell you, these things aren't some sort of windup and there's genuine science behind how and why they work.
I also play a one piece Yamaha soprano sax with a Selmer Concept mouthpiece, Francois Louis ligature and Legere Signature reeds, and a limited edition Trevor James 25th Anniversary alto sax with a Syos Parthenope Signature mouthpiece and Legere America Cut reeds, as well as a Yamaha flute and a Buffet clarinet with a D'Addario Reserve Evolution mouthpiece, BG France ligature and Legere Signature European Cut reeds. I've also got a bass clarinet and another few bits and pieces knocking about somewhere too!
... but ...
Having said all that, there's absolutely no amount of money you can spend that will improve your sound more than practise!