I'm happy to give feedback regarding the first movement, hopefully will analyze the others as time allows.
First off, I have to congratulate you on achieving something of this magnitude! It's evident you know your way around the strings, and successfully writing a string quartet is no small thing. It is, in fact, a form I've not yet attempted because it seems so daunting. Hats off to you, sir!
Now to my comments...
One of the things that grabs my attention immediately, even before listening to the work, is your use of polyphony with these instruments. There is nothing wrong with double- and triple-stops, of course, but I daresay you overuse them, mostly to double notes in chords. (The opening chord, for example, spans 4 Ds, with both the cello and V2 also hitting an F, when the same chord could be achieved without the use of polyphony.) Because of the attack angle required, striking more than one string and sustaining the note lessens the force—not a problem with softer dynamics, perhaps, but it's good to bear in mind that strings are not a piano: more notes don't always equal more volume. Incorporating stops into a work for strings increases the technical difficulty tremendously, particularly if the players are required to hold out such stops. This is not to say that your work isn't playable—I believe it is, for the most part—but it might deter someone from giving your work the live rendition it deserves. Just my thoughts, and I could very easily be wrong about all this.
The score has been very carefully engraved; the amount of time you've spent on this and the level of detail you've achieved are astounding, really. Very, very good! In terms of spacing, it might prove more useful to add just another inch or two between systems. I got lost several times in the score because I jumped one too many staves.
Your articulations might be a little overboard. For example, in meas. 7 (and beyond), you have the cello playing both staccato and accented while at p dynamics. The effect you're looking for could be better realized with just a staccato technique, since the continual accented notes will make the cello a bit louder than p. A similar thing happens with the viola in meas. 9, where you have both a tenuto and an accented note. I think one or the other should suffice. Anyway, these double articulations continue throughout the work. As a conductor or musician approaching this, my impression is that the composer doesn't understand the subtleties of the instruments he's writing for. Plus, it tends to clutter up the score with superfluous markings. These are not egregious issues, of course. But it might behoove you to dial back in future works. 🙂
Your bowing looks good. Slurred passages seem to be carefully considered for playability. Good going!
In meas. 17, you employ both upbow and downbow markings for a single note. I've not seen this device used before, and it seems to defy intuition. (However, I'm not the most knowledgeable person out there, so if it's an established notation, forgive me for bringing it up.)
Musically, this work is amazing! You've created some very good and catchy melodies and strung them together seamlessly with transitional passages that are both challenging and fun to play. Plus, you've spread out the "fun" for all the instruments, not just the violins (as is usually the case). My single complaint with this movement is the recapitulation. It looks to be a verbatim replica, and I would've preferred it be in a different key than the original, or at least changed up a little. The coda is nice and exciting, a perfect ending (in my opinion) to your opening movement.
I know I've pointed out a lot of potential problems, so I want to finish out by emphasizing what a phenomenal job you've done. This is quite an achievement, and took (I'm sure) hours and hours of dedication and perseverence. I am very impressed.
Hopefully, I'll have time to look at the other movements later...