Mobile workstations

Have you found any sites (besides Amazon and Tiger Direct) you depend on for creating a comparison chart of prices and features in deciding which mobile workstation to buy? Ex. Lenovo -vs- Dell -vs- HP- vs- MSI -vs- Asus -vs- Acer with say 5 prices starting at $1,800 going up tp $3,500 - e.g. $1,800 - $2,200 - $2,500 - $3,000 - $3,500 with rows and columns comparing CPU specs (cores, threads, speed), GPU, Motherboard, RAM, etc.? Thank you.