I had a thule rack on a mini truck bed cap before. Was well done, very strong, liked it a lot, but expensive. I think the yak is a round main tube, but I could be wrong. The Thule was rectangular. It did support a good amount of weight. held my canoe, bikes, whatever. I would buy it again. I know people like the other type as well and is just as expensive.
For me the top I had on the pickup had no rain gutters. This was the option I picked as it looked much stronger than the suctioncup things that they had. If you have rain gutters there is no need to drill By the way. I got this rack like 10 or 11 years ago and it still works great and looks good too. Yakima was not as popular at the time and did not have the accessories that they have now.
I bought a used thule gutter mount rack on ebay for $20 five years ago and it still does the job. I just tie kayaks and lumber right to the bars and they work great. The rubber coating and flat surface on the thule bars makes it easy to just strap stuff down.
Have owned both and found the round Yakima bars to be slightly stronger (less flex) than the Thule square bars. Wouldn't really notice with a canoe, but with bikes on it the Thule torqued back and forth somethin fierce.
This was an older Thule setup, so they may have rectified the problem.