**WARNING: NOVEL COMING**
I'm going to be harsh only because you asked for critiques. Just an advanced warning. That doesn't mean that I think the routine is bad, just giving you an alternate viewpoint.
I'm also going to do my long-winded ranting. Sorry, I can't give a short version. Its not within my ability.
--From an overall structure standpoint, I feel you may be overthinking it to a fault. I assume that you are doing ABAB in order to give your chest and back an extra few days of rest in between sessions, but having a 'shoulder day' be your B routine seems counterproductive since shoulders are the one thing that is inevitably going to be overworked in any multi-day split.
--Your volume for chest and back is very reasonable, I see no reason to wait 4 days before working them again. 6 sets for each done every-other-day, with a bit of additional shoulder work every day (maybe shoulder presses/lateral raises/rear delts done in an ABCABC format?) should provide you with your necessary recovery time. I really think that people overdo shoulder training then blame their problems on benching. The truth is, your shoulders get a shyt ton of work with any compound push or pull movement you do. There is a reason that steroid users get blown up delts, its because they end up working their delts damn near every time they step in the gym doing their bro splits--and with the juice, they recover quickly and build muscle rather than get injured.
--Personal preference rooted in science, but I personally never will choose lat pulldowns over pull ups or chin ups if I'm only doing 2 back movements. The bang-for-your-buck is not there with lat pulldowns. 2 movements for such a large and complex muscle group as your back require bang-for-your-buck for maximum results. So always 1 rowing movement (or rack pulls) and 1 downward pulling movement that requires my body being moved through space for maximum muscle fiber recruitment and stabilization. Weighted pulls/chins gotta be the GOAT upper body movement alongside dips, why leave them out?
--Fly's are another exercise that gets thrown out the window for me during a cut. 1 set right before I leave just to get a pump is about it for me. You are inevitably going to be depleted when eating a caloric defecit, so vanity pump exercises aren't a priority. Retaining strength and forcing your body to hold onto its muscle tissue should be your priority. That glycogen pump will come back very quickly later once you stop dieting. If you were still doing a bro-split during your cut then keeping the 3 sets of flies is fine, but you are limited by time and energy. The dips option you listed is so much better, it is not known as the 'upper body squat' for nothing. Forward leaning dips work damn near every muscle in your upper body in some fashion...front and back.
--Never ever would I do heavy squats after doing upper body. 5 rep squats are a CNS killer, waiting until the end of your workout after you are already taxed is a recipe for under performance and possibly injury if you have existing form flaws (which most people do). I agree with your idea of doing ABABAB for squats/leg press. Squatting 3 times per week on calorie restriction is rough
--Way too many reps for your back work. There isn't a power back movement to be found on there.
OK I think I'm done interjecting my own thoughts.
Have you considered a routine that perhaps keeps a similar structure between days, but alternates heavy/light/medium instead of alternating the exercises?
Something like:
Day A (strength):
3 sets squats, 5 reps
4-6 compound chest sets, 5 reps
4-6 compound back sets 5 reps
2-3 sets Military Press, 5 reps
2-3 sets hamstrings, 5-8 reps
2 supersets for bicep/tricep/forearm/calves/abs, any rep range
Day B (pump):
3 sets leg press, 15 reps
4-6 compound OR squeezing chest movements, 15 reps
4-6 compound OR isolation back movements, 15 reps
2-3 sets lateral raises or rear delts, 15 reps
2-3 sets hamstrings, 15 reps
2 supersets same as above supersets
Day C (hypertrophy)
3 sets squats, 8-12 reps
4-6 compount chest sets, 8-12 reps
4-6 compound back sets, 8-12 reps
2-3 supersets for military press combined with rear delts or lateral raises, 15 reps
2-3 sets hamstrings, 8-12 reps
2 supersets same as above supersets
Just something I thought up real quick, I didn't go over it with a fine toothed comb so I might be missing something
