Both workouts are good.
I like S&H because it is very versatile, and it's one of the only Cathe workouts that actually has enough recovery time between sets (the others, I put in my OWN recovery time!). I often don't use the '6-up, 2-down' rep speed Cathe does, but prefer a 5-up/3-down speed or, for shoulders, 4-up/4-down.
You could easily use S&H chest/back as the basis of your upper body work, and combine it with a shoulder/arms workout on another day (it's not a Cathe workout, but P90X has a great Shoulder/Arms workout that it would pair nicely with). Even doing just chest/back when you are short on time also hits the biceps, triceps and shoulders as assisting muscles.
That being said, I have only used S&H lower body once or twice, and my knees did NOT like the slow lunges. I prefer GSL or PLB.
Gym Styles is a great 3-day split. I like all the workouts. The pace is slow enough to use heavier weights, and the use of bands adds an extra burn. I do put longer breaks between body parts, and sometimes between sets with one body part, because I am more interested in strength gains than in endurance. The GS upper body workouts flow from one body part to the next without sufficient, IMO, recovery between them when done "as-is." But that's an easy "fix" by just pressing pause while you walk around, sip some water, and set up the weights for the next segment.
Of the two (GS vs. S&H), I definitely get more use out of GS, since I use ALL the workouts.