There are a few different factors that could contribute to making a work boot the "top of the line." This would likely include features such as waterproofing, insulation, a comfortable and supportive fit, durable construction, and slip-resistance. Some specific work boots that might be considered top of the line include the Caterpillar Men's 2nd Shift 6" Plain Soft Toe Work Boot, the Timberland Pro Men's Pitboss 6" Steel-Toe Boot, and the Georgia Boot Men's Loggerboot G8374 Work Boot. All of these options are available in a variety of sizes and widths to ensure a good fit, and they all boast features like waterproofing, durability, comfort, and safety toe protection.