Rack science: What do you want to carry? Thule and Yakima are analagous to Cadillac & Lincoln.Both are excellent. Parts are not interchangeable, but adapters are available from either company to fit the others.Towers and bars are the foundation. Think about what you want to carry when choosing bar length; longer than recommended if you want a box and a bike, or ski mount. Also , don't forget locks for the towers and your ancillary mounts.
As a Thule dealer Email me and I can set you up, though I can also access most Yakima, too. Car make and model are crucial as is what you want to carry, so bend your mind that way, carefully.Once you pick a manufacturer, stick with it for all accessories as fit and finish will be cleaner than adapters