A race or aero fit jersey is designed to sit very close to your skin with minimal excess fabric, which is exactly what you want when speed matters. It'll feel surprisingly tight standing up, but once you're in your riding position, the pre-shaped sleeves and articulated cut should feel just right. That snug fit is what reduces aerodynamic drag and keeps moisture management working efficiently.
Race fit makes the most sense if you're regularly racing, doing time trials, or pushing the pace in fast group rides where every watt counts. For those scenarios, the aero advantage is real and noticeable.
However, be honest about your priorities. If your rides regularly stretch past three or four hours, or you prefer comfort over marginal speed gains, a club fit might serve you better. Also, if you're between sizes, sizing up one size in race fit is a smart move to avoid restricted breathing.