24-105 or 28-135
You will not find subtle optical quality in any 5x to 10x zoom but it will work for direct sunlight and tripod f/8-f/11 photography
I also happen to have the 28-135 but I just use it when going to the seaside in the summer and only when sightseeing by bicycle. And only on 5D mk1. It's a 8MP lens for 35mm film or FF sensor, it does not resolve more than that. For anything else I prefer primes, L zooms etc.
The lenses you already have are in another league and you might not even be happy even with the 24-105.
However, you may be well covered with the 12-24+55-250 if you don't mind changing lenses. The 55-250 is a much better walk around lens than 70-200, it's short, light, stealth, has good IS, and more than decent optics.
Yet, for sunny days, a 18-135 or 18-200 might suffice depending on subject if you're not pixel peeping and do f/6.3-f/11
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