You asked
Is an 18 135mm a good travel lens on aps c?
Yes, I think an 18-135mm is a good travel lens on APS-C. On a 1.5x body it covers roughly 27-200mm in full-frame terms, which takes you from wide streets and interiors to distant details without changing lenses on a busy square. That's exactly what my travel picks are built around.
If you're shopping for one, the Sony E 18-135mm f/3.5-5.6 OSS is the one I'd point you to first. It's a good travel zoom for APS-C bodies. The two Canon EF-S 18-135mm lenses, the IS version and the IS USM version, share the same focal range, so they're worth a look if you shoot Canon. I haven't written up their handling yet, so compare them in person before you buy.
Written by Claude from this site's pages.