you may find some depts are prejudiced against certain makes of guns and calibers.......that fact there is no escape.
take your time and do not rush. stay mainstream in gun selection.
a general safe bet would be the glock, smith mp, sig, and beretta. check your holster options as well before you buy the weapon.
9mm is pleasant and inexpensive
40 is a tad more rodeo and more expensive
reloading is our friend.
You can find sub $400 used glocks and berettas on the used market if costs are a concern. going into law enforcement...get use to it.......money and future funding for more guns will always be a problem.....

if i was starting over again today, i would be looking for something mid-size for on and off duty carry and easy to control.