Which AC unit is better for my home, a 3.5-ton or a 4-ton?

Which AC unit is better for your home, a 3.5-ton or a 4-ton, depends on your home square footage, insulation, climate, and Manual J load calculation, and you should not guess because oversizing causes humidity problems and short cycling. One ton equals 12,000 BTU per hour of cooling, so 3.5-ton equals 42,000 BTU and 4-ton equals 48,000 BTU, difference is 6,000 BTU or about 15 percent more capacity. For typical 2,000 to 2,400 sq ft home with decent insulation in moderate climate, 3.5-ton may be sufficient, while 4-ton may be needed for 2,400 to 2,800 sq ft or for poor insulation, high ceilings over 10 feet, large west-facing windows, or hot climate like Texas. Choosing 4-ton when 3.5-ton is correct causes oversized system that short cycles, runs only 5 to 10 minutes, does not remove humidity, leaves home feeling clammy, and causes more wear and higher electric bills. Choosing 3.5-ton when 4-ton is needed causes system to run continuously on hottest days and not reach set temperature. Proper way is to have HVAC contractor perform Manual J load calculation that considers insulation R-value, window size and direction, air leakage, and occupancy, not just square footage. For most 2,200 sq ft homes, 3.5-ton variable speed is better than 4-ton single stage because variable can ramp up when needed.