Schwalbe Marathon Plus and Continental Gatorskin are two of the most established and most-discussed lines of tyres on this site (170 results and 89 results respectively if you search them in "Questions").
If you had to choose one over the other for a five-mile urban commute (trying to avoid a couple of smashed bottles each way) and could buy them at the same price, which would you choose (taking into account rolling resistance, weight, puncture resistance, and other relevant factors)?
I would pick neither. Both have way too high rolling resistance.
I have used Continental Grand Prix 5000 for the last 2000 km. Not a single puncture in that period.
The problem with Marathon Plus is its ridiculous rolling resistance. It's clearly out of the question.
Gator Hardshell has similar rolling resistance to GatorSkin. I have simulated GatorSkin and GP 5000, and the result is you lose 1.7 minutes with GatorSkin when compared to GP 5000 in a 5+5 mile commute there and back. Puncture repair with proper tools takes perhaps 5 minutes, so if you get punctures more rarely than once every three days, it's a better choice to minimize rolling resistance than it is to maximize puncture resistance.
Somebody could argue that arriving 5 minutes late at work is alone a reason to go for more predictable commute time with high puncture resistance and high rolling resistance tire, but then again 5 minutes is the difference of headwind and no headwind, so you have to be prepared to be 5 minutes late anyway.
Note my 2000 km during which I had no punctures with GP 5000 corresponds to 124 working days with 5+5 mile commute there and back. Way more than 3!
But, if there was no other choice than Gator Hardshell and Marathon Plus, I would clearly pick the Gator Hardshell and suffer its high rolling resistance, because the rolling resistance of Gator Hardshell is still better than that of Marathon Plus.
Weight is not a consideration. All similar tires weigh about the same, with perhaps minimal differences due to bead material (kevlar vs steel wire). Besides, low weight is overrated. Typically what determines your speed are air resistance and rolling resistance, not weight. Especially in consumable parts like tires, chains, sprockets, etc. saving weight is not advisable because you have to pay a lot to get a lightweight product that will last only few thousand kilometers.
About the width: I currently use 28mm due to historical reasons (when I bought my first road bike tire, it was GatorSkin 28mm because no wider variant was available back then). I mainly have stayed with the 28mm width because I have found it to work for me and have high investment in 28mm equipment. If I was to choose a tire today with no existing stock, I would go for 32mm.