The benefits of being well dressed are numerable, and fairly easy to acquire for only a modest initial outlay. How you are dressed affects the way that other people react to you, and in turn how you react to them. Think about the way you react to people based on how they are dressed, be honest, you don't "treat everyone the same, no matter how they are dressed" even if you say you do. It also subconsciously affects your posture, it may take a couple of months to feel comfortable in a suit, but when you do you will find that you hold yourself differently; the fit of a well cut suit will be more comfortable with good posture. This makes you feel more confident, and influence peoples opinion of you more positively leading to you being offered more interesting or lucrative positions, if you wish to apply for them. Above all being well dressed is a form of good manners, you are making an effort not to offend in any visual way, but to dress in a manner that is pleasing, or at the least inoffensive, to others.
I for one prefer a dark three-piece suit, shirt with french cuffs, and a tie. I am regularly the best dressed person in the room, if not the company, our MD doesn't even wear a tie. There is ample room for personalising you appearance with cuff links, ties, pins and watch fobs, as well as rings and other small accessories to please most people.