Where do you buy your sensors, and which ones do you use? Sounds like they are all over the place so they need power and wireless (or a lot of cabling....)
the motion sensors and door/window sensors are zwave.
They are battery powered, but i've had the oldest ones for almost 2 years now and haven't had to replace the batteries yet, and when I do I can get a pack of like 10 for $15 so it's not bad.
All of the light switches are zwave as well, and they go in the wall behind the toggle switches, so from the outside you can't see any difference.
I get most of them from amazon, and i've used a bunch of vendors over the years. Aeotec, ecolink, linear, and a few no-name brands.
By far my favorite was the aeotec micro smart switch energy gen2
It's not sold any more, and it's not zwave plus, but I have like 12 of them and they are by far the best i've used. They are small, run consistently 100% of the time, have good range, and more.
I have 2 of the aeotec nano switches which are zwave plus, but they are also $60 so it's almost double the money...
I've also used fibaro but ended up removing it because there was a delay between when i flipped the toggle and when it would turn the light on, and that was not okay in my book.
I am looking to replace the light switches with zwave-plus modules simply for the extra security, but i'm not in a massive rush.
In the sensors world, i use ecolink's door window sensors. They are cheap and work well enough, although I did have 2 out of about 20 that were bad and needed to be replaced shortly after installing them.
I am also trying out zooz 4-in-1 sensors for motion right now. They work pretty damn well with a lot of control over sensitivity and range, so I'm happy.
For the garage doors I use linear/gocontrol's GD00Z-4 modules, and my door locks are kwikset with a zwave plugin board, and there are a few plugs around the house from various companies that all have worked perfectly so I don't really have anything bad about them (ge, aeotec, r-tech)