Eye protection and visibility are major factors to consider when buying goggles for noncompetitive lap swimming. Various concentrations of chlorine in lap pools cause eye irritations. Seeing clearly is an important part of avoiding collisions in crowded swimming pools and swimming in pools without boundary markers. Goggles need to be comfortable since they will be worn during a workout that can be an hour or more. Swim goggles are vital sports equipment for lap swimming.
To prevent eye irritations the goggles must not leak. Leaking goggles can fill up with water and obscure vision. This distraction requires that you stop your workout to empty the water out of your goggles. A press on fit is a good indication that the goggles will not leak. Simply try on some goggles without using the strap. If they don't fall off immediately they are making a good seal. Barracuda Swim Goggles" with their foam gasket are notable for not leaking. Occasionally condensation will form on the inside of the lenses of the goggles even if they don't leak. Sometimes a little saliva on the inside lenses on the goggles will cure this problem. Anti-fog goggles have goggle treatments which coat the lens with hydrophilic (water loving) chemicals which pull the water flat to the len's surface much like the mucus in your saliva.
Swim goggles have adjustments to make them more comfortable. The head strap also serves to keep goggles from slipping and leaking. Some head straps can be adjusted quickly while others require needle-threading skills. Look for head strap fasteners that can be adjusted by sliding the strap out of a slot and pulled easily. If the strap is tight enough to prevent slipping and leaking, it should also be comfortable. Hard plastic goggles without enough foam become uncomfortable.
Some goggles have an adjustable center or nosepiece that allows the width of the goggles to be changed. I have had the nose piece cut into my skin. I have found that the soft one-piece construction of some TYR or Speedo goggles to be most comfortable.