The short answer
Seamless gutters are better for most homes. They are formed on-site in one continuous piece between corners, so there are no seams every 10 to 20 feet to leak, separate or catch debris. Sectional gutters cost less up front and are DIY-friendly, but their joints are where most gutter leaks start.
Leaks and maintenance
Every seam in a sectional gutter is sealed with caulk or a connector. Seasonal expansion and contraction wear those seals out, which is why sectional gutters often drip at the joints after a few years. Seamless gutters only have joints at corners and downspouts.
Cost
Sectional gutters from a home store are cheaper to buy, especially if you install them yourself. Professionally installed seamless gutters cost more up front but usually need fewer repairs.
Looks and sizing
Seamless gutters are cut to the exact length of each run and come in many colors to match your trim. They are available in 5-inch and 6-inch profiles, sized to your roof.
When sectional makes sense
Short runs on a shed or detached garage, or a quick DIY repair, are reasonable places for sectional gutters.
Get a free estimate (636) 262-2898
Related: Seamless Gutters