I think the OP is being genuine when he asks about 3rd party lenses.
I, too, have been frustrated for years at the third party manufacturers. Why? Because they seldom make anything better than the Canon L series equivalents. It seems at times like the 3rd party manufacturers think that we are all trying to save money, when in fact there are some of us who will gladly pay more than we will for Canon L glass if somebody made something different, or better.
Tapeman wrote in post #18294621
I ..... would consider a lens made by someone else if it were superior in image quality and convenience.
I should mention I like zoom lenses as apposed to foot zooming.
What lenses should I be considering instead of Canon?
One lens that fits the parameters you have set is the Sigma 300-800mm.
I have this lens because it offers something so very different than any Canon lens. .No Canon offering provides a zoom in focal lengths any longer than 400mm. .I find the 300-800 range extremely useful and the optics are excellent.
However, it does not have any Image Stabilization, so you need to have, or develop, very good long lens technique to get the most out of this lens.
"Your" and "you're" are different words with completely different meanings - please use the correct one.
"They're", "their", and "there" are different words with completely different meanings - please use the correct one.
"Fare" and "fair" are different words with completely different meanings - please use the correct one. The proper expression is "moot point", NOT "mute point".