Battery - Shut down or sleep an MBP
There are two factors that govern the life of a battery:

Age
Charge Cycles

The biggest factor is age.  Math Finds Top Culprit as Lithium Batteries Age

...a battery ages, or degrades, whether it is sitting on a shelf or
in use. The main cause of lithium-ion battery aging is the continuous
formation of the solid electrolyte interphase (SEI) layer in the
battery. The SEI layer must form for the battery to work because it
controls the amount of chemical reactions that occur in the battery.

The next is cycle count. A complete discharge and recharge is one cycle. A 20% discharge 5 times is one cycle, a 5% discharge 20 times is one cycle.
Whether that cycle takes a half day, a full day or a week all depends on how you use it; sleeping will put a very, small draw on your battery versus being off but the difference is almost negligible - I am assuming that you are not sleeping your MacBook for weeks at a time.
Even when you keep your MBP plugged in, you are reducing the per day cycle count; however you are not eliminating it.
Why does cycle count matter?  From the article again...

As the battery is continually used, however, small-scale side
reactions build up at the SEI layer, which decreases battery
capacity—how much of a charge the battery can hold.

Bottom line
It's doesn't matter.  You can expect to replace your battery somewhere between year 3 and 4.  Can you get longer?  Yes.  Can it be shorter?  Yes.  It's tough to know exactly when, but choosing &quot;sleep&quot; over &quot;power off&quot; isn't going to make a big difference.