It depends if the bike is for work or leisure.
If you leave your bike unattended all day in a high-risk area, sooner or later someone will mess with your QRs or even remove them. I have used solid axles with a big track nut for security, but a secure locking (not just allen key) QR is better.
carrying the wrench is a nuisance but I carry a pump and repair kit the whole time anyway. I prefer a ring to a cresent wrench; you can apply some foot force to the nut.

Seatpost QR?? waste of space. Use a cheap post/saddle with a nut and no-one will steal it.
Sus post: too much stuff. They weigh more and wear out after heavy use.

I see people locking their fancy bikes up, removing the front wheel to lock to the rear, then removing all the lights/computer etc, then the seatpost and saddle. How far can you ride the time it takes to lock/unlock the bike? I'm sure the overall journey would be faster with a low-tech beater bike where you can safely leave all the bits on the bike.