Good point about Field Hospital - that actually might save some garrison lives.
It really depends on what you have in excess and what you can't spare. Manpower? Equipment? Tech research? Military Police isn't the no brainer it used to be. Instead of +100% suppression, its only +20% and +10% for each level after that. Now I'm playing the UK, but yes the UK does need to worry about resistance and compliance, but of course by no means like the axis (although will be interesting to see my resistance/compliance issues once I take Italy).
In occupied territories window, there is the default garrison icon in upper left. Click that to see the primary garrison template list, which is really all of your templates it seems. However, the columns have incredibly useful info to analyze each division for:
a) manpower per suppression
b) production cost per suppression
c) hardness
The stats per division don't matter at all, as divisions are literally abstract with this mechanic and fractional divisions are assigned where needed. So, going back to my question above regarding what you have in excess and what you have in need, use this template list to figure out which is the best. Lol, and its funny to see how horribly inefficient armored divisions are for garrison duty.
Lastly, about suppression and resistance reduction rates....yes and no is the answer. If you have fulfilled your garrison requirements, then there is no template in the world which can reduce resistance faster. For that, you need to change collaboration law. Some will reduce resistance faster than others, but the "better" ones for squashing resistance require more garrisons usually.
And as a bonus, check out the garrison logs. You can see your losses, when and where (like combat log). From there you can see if you are taking more manpower losses, or more equipment loss, lol or BOTH...and can then adjust according. Maybe add armored cards for some hardness to save lives. Maybe remove MPs if you want to save precious support equipment. Its all up to you.