amfoto1 Loc: San Jose, Calif. USA

Definitely the EF-S 18-135mm USM. It will replace your old 18-55mm and, to some degree, 55-250mm (though, depending upon what you shoot, you might eventually end up getting 70-200, 70-300 or 100-400mm to more fully replace the longer telephoto).

When I want to "travel light" with a Canon APS-C camera, I often take EF-S 10-22mm, Tamron 60mm f/2.0 macro/portrait, EF 28-135mm, and a 300mm f/4L IS with 1.4X teleconverter. If I were buying today, I'd happily get the 18-135mm USM, in place of the old 28-135mm.

dsmeltz Loc: Philadelphia

Here are a few articles

http://www.switchbacktravel.com/best-lenses-canon-80d
http://www.smashingcamera.com/2016/04/7-best-lenses-for-canon-eos-80d/
http://cameratimes.org/best-lenses-canon-eos-80d/

nhastings Loc: Telluride, CO

I have been using the 18-135 on my Canon 70D for years with great results. When traveling I usually take 3 lenses but 95% of the time just use what's attached to the camera, the 18-135. The older I get and the more I travel, the less I want to carry around a suitcase or backpack full of equipment. Certainly your choice but my opinion is you will do quite well with the one lens. Good luck and have a ball.

ballsafire Loc: Lafayette, Louisiana

If you can afford the 24-105 F4 L lens, I'd try that one (sells for abt. $1,200.00) but if the price is too much then I have some advice for you. I'd get the "Macro" if you can find it on line: (1) ask if the word "Macro" is printed in yellow letters at the close focus end of the distance scale. (2) the words "made in Japan" are printed in white on the front of the lens -- on the front of the lens it is written "CANON LENS MADE IN JAPAN 58mm". I have the Taiwanese version which I like but the Japanese versions are extremely rare. Both these versions are now discontinued but available on line used, maybe. Mine says "CANON INC." along with "CANON ZOOM LENS EF 28-105mm 1:3.5-4.5 II USM". Try Ebay or Amazon under "used" with lens name. The MACRO has 7 blades instead of 6 (known as "Mark II"). All newer models are inferior and have "f/4-5.6" instead of "f/3.5-5.6". Happy search -- Price? I got mine for $160.

Architect1776 Loc: In my mind

I have a 7D and have the 24-105. Love it and would recommend it to you. Very good quality images.

mjgreen53 Loc: Christchurch NZ

Thanks for the feedback. Lots to choose from and now for my homework to narrow down my decision.

ballsafire Loc: Lafayette, Louisiana

I neglected in adding that I have a Canon T1i/500D crop APS-C (1.6) camera with about 10 lenses including 4 primes. I only have two "S" lenses (my Kit 18-55mm f/3.5-5.6 zoom and 10-18mm f/4.5-5.6 STM).

bigwolf40 Loc: Effort, Pa.

This is just a suggestion to look at the new Tamron 18-400mm lens. This will give you a lot of coverage. I also have the 80D and am thinking of getting this lens. I'm in no rush so I'm going to wait until around thanksgiving and black Friday to see if it will go on sale. Right now it's $649 dollars U.S. ....Rich

JohnH3 Loc: Auburn, AL

I have a lot of very nice lens, but with my crop sensor camera the EF-S 18-135 is the go to lens. It just works and does the job.

amfoto1 Loc: San Jose, Calif. USA

Another consideration...

If buying the 80D in kit with a lens, it's usually bundled with the EF-S 18-135mm IS USM (the latest and greatest, fastest focusing version).

Buying it that way, in kit, right now you get camera and lens for $1600 (there's a $200 Instant Rebate offered on the kit). The camera alone costs $1200. So basically this means you're getting a $600 lens for $400.

The other kit offered with 80D includes two lenses for $1500. The lenses included are EF-S 18-55mm IS STM and EF-S 55-250mm IS STM. Those aren't bad either, but the EF-S 18-135mm IS USM is better... faster focusing, better built, more versatile range of focal lengths in a single lens.

The EF 24-105L isn't offered in kit with the 80D. It's normally only offered in kit with a full frame camera such as the 5D Mark IV.

For still photography and travel, if I were to consider any other lens than EF-S 18-135mm IS USM, it would be the EF-S 15-85mm IS USM.. That's a great lens that goes a little bit wider, so may not need to also buy and carry an ultrawide such as the EF-S 10-18mm IS STM (under $300) or EF-S 10-22mm USM (about $600). However, the EF-S 15-85mm IS USM isn't offered in kit, is only sold separately and is a fairly pricey lens at $800. So to get an 80D and the EF-S 15-85mm IS USM would cost $2000.

A third kit option is video-oriented... 80D with EF-S 18-135mm IS USM and an external microphone and the PZ-E1 Power Zoom module, $1700 (...current price at B&H, after a $350 Instant Rebate).

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Very good advice, as usual!

ballsafire Loc: Lafayette, Louisiana

dsmeltz Loc: Philadelphia

Right now you can get the 80D EF-S 18-135mm f/3.5-5.6 IS USM Kit Refurbished for $1,149.00.
http://shop.usa.canon.com/shop/en/catalog/eos-80d-ef-s-18-135mm-f-3-5-5-6-is-usm-kit-refurbished?searchTerm=80D