Hull speed is not a particularly good measure of sailing performance. First the formula was designed to estimate the hull speed of commercial sailing vessels back in the 1700s, when hulls were blunt nose, beamy, and heavy. Waterline length does make a difference but hull form makes a big difference. Some hull shapes are slipperier than others (to use a highly untechnical term). Also, as the the boat heels the waterline can change and affect hull speed. It is not unusual for many boats to theoretical hull speed under the right conditions.
Weight is also a tricky measure. All things being equal a lighter boat will accelerate quicker than a heavier boat, but it will also slow down quicker when the wind drops or it hits a wave. Heavier boats will have more momentum for any given speed than a lighter boat which will allow them to carry on further during lulls with less speed loss and punch through waves with less speed loss. The lighter boat will be "quicker in the corners" because it will accelerate faster out of a tack. Competitive sailors prefer lighter boats because they will tack more often to take advantage of wind shifts.
Trying to decide which boat is faster based on paper characteristics is complicated. In addition to weight, sail area, sail area to displacement ratio, beam, waterline length and other factors contribute to boat performance. Hull shape also matters and can affect boat speed on different points of sail.
On the race course and assuming a fair handicapping system (what maybe a rash assumption) there are many more factors that are important, boat prep, sail design and age, skipper's skill, local conditions, crew skill quick come to mind. Skipper skill is probably one of the most important. A highly skilled skipper sailing a less optimized boat will almost always do better than an unskilled skipper sailing a highly optimized boat.
If speed alone is the main decision point, then looking at the PHRF ratings is probably the best indicator of relative speed. It is simple, allegedly based on actual performance, and commonly used. Search for PHRF ratings for each boat.