Let's go over the alternatives proposed so far, plus one of my own:
Foo et al. proposes that the sky is blue [ 1 ]. This is in contrast to Fizz and Buzz, which maintain that the sky is more greenish [ 2 ].
The most clean alternative, but I see where the OP is coming from. If everybody does that, and assuming that especially in large cooperations alphabetical ordering of authors becomes natural, it certainly becomes an advantage to have a last name starting with "Aa".
[ 1 ] proposes that the sky is blue. This is in contrast to [ 2 ], which maintains that the sky is more greenish.
This is the solution proposed by AJK in her/his answer. Many "style purists" don't particularly like this writing, as it essentially uses references as nouns rather than as annotations to the text. I personally don't mind this style, as I think it communicates intent fairly well, and that should be what it's all about. However, be wary that some might find this style of writing to be "wrong" and complain about it.
The paper [ 1 ] proposes that the sky is blue. This is in contrast to the paper [ 2 ], which maintains that the sky is more greenish.
I see no real advantage of this phrasing in comparison to the previous approach - it's only longer. Note that even in this version the references are not really annotations, but part of the text itself. That is, if you remove the references from the above sentence, it does not actually make much sense anymore (unlike in the first variant).
Ref 1 proposes that the sky is blue. This is in contrast to Ref 2, which maintains that the sky is more greenish.
I have seen this variation maybe two or three times in the wild so far, and I am not sure why you would use it over the second variation. The only advantage I see is that it "looks" more like a regular English sentence, but it still has the problem that the reference is part of the sentence rather than being an annotation.
A common thought in research is that the sky is blue [ 1 ]. However, some challenge this by arguing that the sky is more greenish [ 2 ].
My personally preferred option is to rephrase the statement to focus on the thought or result itself, rather than on who produced it. If you do that, the problem tends to go away naturally. Even independently of writing style, I have always found texts to read better once you remove all the "A said, B said, C said" boilerplate and focus on what has actually been said.