The most well rounded lens for Canon

I'd suggest a Canon 28~135mm lens till you learn more . It's not expensive and can do a fairly good job. That lens is a "kit" lens that Canon sells along with their cameras. Sort of a package deal. A lens is something you will keep forever, But as you do more shooting, you will have more specific needs, and will want to purchase a lens that is of higher quality to meet specific types of shots. I would suggest a Canon 24~105mm F4. I use this lens as my walk around, as it meets most of my requirements. Working photographers have lots of lenses. I use this lens for head shots, weddings, & many special events. But It won't do for sports and concerts.

When shooting portraits; distance from the subject, long focal length, and large apertures, will contribute to the bokeh effects. Head and shoulder shots are easier to get more bokeh than full body shots. I use Canon 24~105 F4 lens and get excellent results. Putting aside the issue of bokeh, I use that lens in my studio for corporate head shot work & it is very versatile for weddings too. When shooting panoramic scenes: Distance determines what is in focus. I had the 24~70mm F2.8 and sold it right after doing one wedding. It was way too heavy and I needed the extra zoom, since sometimes I am not able to get close. For me the Canon EF-24~105mm F4 is a good all around lens. For those tight spots where I cannot get back far enough, I bought a wide angle lens EF-S 15-85mm f/3.5-5.6 IS USM to fit my 7D. It is tucked in my bag for those special occasions. Again, I repeat myself, there is a lens for different shots, for instance, shooting sports. For that I need my long zoom Canon EF-70~200mm F4. ( couldn't afford the 300mm) .