Well, I have a different opinion from others.
I went through the same thing 6 months ago, and started with just my kit lens.
First lens I bought was the 17-40mm f/4 L, (I love landscape, walking/hiking around) and yes, if you're taking pics at dawn/sunset, you'll need tripod and doing those slow exposure for seascapes, you definitely need a tripod! At that time, budget was a problem for me so I didn't buy the 17-55mm, and I didn't get the 15-85mm, because I'm planning to upgrade to FF in a couple years, so those were kinda the reasons why I decided on the 17-40mm.

On the long side, I later bought the 70-200mm f/4 L IS, because it's light-weight and easy to carry around, and with stunning IQ even compare to the f/2.8 version I. And I'm nowhere near a professional, and I mainly use it for landscape and in good light, so I'm really happy with my selection of lenses.

Hope my experience helps.

FYI, both lenses create amazing results, the 17-40mm might be an old lens, but it's a good lens for its price, and both are weather sealed for long hikes or humid weathers!