I never really watched the first two seasons before, I only knew some of the basic plot elements thanks to Church's time travel shenanigans in season 3. As rough looking as it was and as strange as the old voices sounded back then, I still found myself really enjoying them.
There's just something about how the characters bounce off of each other and how the jokes came out that really jived with me. It's hard to describe.
Then I got to rewatch the seasons I was familiar with and I honestly got to say that they were comedic masterpieces. By Season 3, the plot and situations the characters find themselves in just get more and more absurd. Fighting against the slowest moving army of robots ever, befriending a talking bomb, the Reds nearly tearing themselves apart due to their absolute stupidity and their refusal to properly communicate, having to communicate with an alien that only says "Honk" and "Blarg", said alien impregnating Tucker, Grif's colorblind sister mistakenly joining her brother's team and everything involving O'Malley coming to a head at the end.
The whole thing was just so batshit insane and ends with roughly a third of the cast dying in an explosion and the Reds and Blues going back to doing nothing. It was sort of both bittersweet and hilarious at the same time.
I remember watching Season 6 and parts of Season 7 and being kinda mixed on it. It just felt kinda weird having an actual serious plot thrown into the midst of a show like Red vs. Blue. I rewatched them as well as 8-10 and I felt kinda mixed about it all. When actually focusing on the Reds and Blues, the writing and humor was still spot on, but the (admittedly incredibly well animated and choreographed, especially considering the limited tech and budget at the time) fight scenes and everything about the Freelancers just felt incredibly jarring. None of it was bad by any means, and I did enjoy everything involving Church and Tex. I just kinda missed the general feel of the early seasons and how generally out there they were.