In general, the more you design a lens to be able to do, the less it will be able to do all of them well. That's why there is no such thing as a "best" lens. There are only lenses that are "better" or "worse" for a specific task. The more disparate tasks you expect a lens to be able to do, the less you can expect such a lens to do any of those tasks as well as a lens designed solely for that single task.
Most of the class of zoom lenses considered "travel lenses" are for APS-C or smaller sensors, where the compromises of designs with focal lengths that may range from as wide as 20mm to as long as 300mm will be less apparent. The market doesn't really seem to demand many lenses in the way of 10X or more zoom ranges for FF lenses. This question and its answers cover some of the reasons why there's not much demand for such lenses: 24-200MM lens for Nikon D850? There are a few 28-200mm "super zooms" out there for FF, but they may or may not allow you to take the kinds of images you want.
Both the EF 24-70mm f/2.8 L II and the EF 24-105mm f/4 L IS are pretty good lenses. Both offer something the other does not.
- The EF 24-105mm f/4 L IS obviously offers focal lengths in the range from 70-105mm that the other lens does not. It also has Image Stabilization. It's built like a tank and can take a lot of punishment and still go on working well. It only costs about 59% what the other lens costs.
- The EF 24-70mm f/2.8 II obviously offers an extra stop of aperture. It's also as sharp or sharper at common focal lengths when open at f/2.8 than the 24-105/4 is at f/4. It costs almost twice (1.7X) as much.
In fact, the actual real brightness difference between the two lenses is almost two stops. The 24-70/2.8 II is T-2.8 at 24mm, T-2.9 at 35mm and 50mm, and only climbs to T-3.1 at 70mm. That is only slightly dimmer than it's f/2.8 minimum aperture. The 24-105/4, on the other hand, at T-5.1 over most of the zoom range, is closer to f/5.6 than it is to f/4.
You need to ask yourself which is more important to you: a wider focal length range and IS or wider maximum aperture? The very robust construction for about 40% less or the slightly sharper performance?
In the end, what will be the "best" travel lens for you will not be the same lens as the "best" travel lens for many others. Similarly, what is the "best" lens for you to take some types of photos you wish to take might not be the same lens that is "best" for you to use to get other types of images you want.
Lens selection is a highly personal decision.Often different factors having to do with lens performance, focal length, maximum aperture, price, size and weight, etc. must be weighed against each other in order to select the one that works "best" for you.