Hi All,
Would love some input best door sensor to get for new home automation user. (I have ST, Google Home and a DoT)
I dont want spend alot of money as well, just try and see if i like the way it is works and then add-on to it.
Any advice will be appreciated.
Thanks,
Mo.
What country do you live in? This will impact what devices are available.
I am in US.
Haha
You beat me by about 30 seconds 
I’d grab the ST multipurpose - great price.
Wait for @JDRoberts to reply. JD will point you in a direction that may make searching endless posts a lot easier to weigh out a decision based on all your factors.
@JDRoberts Please.
I agree with the ST Multipurpose sensor, especially at that price. Also, people have a lot of good things to say about the Visonic MCT-340 E and they’re really cheap right now, too ($14.99).
JD is currently in the middle of replying. Be patient
LOL!
OK, OK I was going to leave this for other people to answer as I’m not feeling very well today, but here I am.
First the long answer. 
There’s no one best because different people have different needs and preferences – – and budgets!
You might first take a look at the device class features FAQ, because it will explain what some of the different features are that a model might or might not have, and that can help you decide just what you might be looking for.
Short answer 1: Lowes
Now the short answer. If you want relatively inexpensive, reliable, officially certified to the same protocols that SmartThings uses, and you’re OK with zigbee sensors, the community consensus seems to be for the Lowe’s Iris sensors, particularly if you can get them on sale or if you can use an in-store coupon.
Be careful because Lowes sell several different models, and not all of them work with SmartThings. So read the reviews to make sure it’s the right model. And write down the model number before you go to the store if you going to buy in store, because the clerks won’t have any idea of the difference between the different models.
https://www.lowes.com/pd/Iris-Iris-1-Sensor-Indoor-Door-And-Window-Sensor/999925302
Short answer 2: some zwave options
If you want Zwave sensors, Econolink seem to be the fastest inexpensive zwave model ( still slower than the zigbee ones, though) , but the gocontrol/Linear/2gig are often on sale at Home Depot in a box set of 2 contact sensors and one motion sensor, and can end up being a little cheaper. All of these are reliable and officially certified, it’s just that in general Z wave sensors tend to be slightly less quick to respond than zigbee sensors. Also the battery life won’t be quite as good as with the zigbee sensors, and the sensors themselves are usually bigger.
Short answer 3: cheap but flaky
If you want super super cheap but occasionally flaky sensors that are not certified, you could take a chance and go with the Xiaomi brand of zigbee sensors from China. They seem to be pretty well-built, but they are intended to work with their own gateway not anybody else’s, and, like I said, can be flaky.
But if you want to consider the Xiaomi, make sure you read through the following thread first. Yes, these are super super cheap, often $10/sensor, but you will see that people also have a lot of different kinds of problems with them. So know what you’re getting into. Also you probably have to buy them from gearbest, which is a Chinese importer, so they can take a long time to arrive and the returns policy is not as good as Home Depot or Amazon or Lowe’s.
If you want an easy path, you need go after native smartthings stuff. If
you are adventurious, you could save a lot with Xiaomi sensors.
The link below has one community member’s review of three popular sensors.
Dont see the link?
There ya go Mohit.
That should help you weigh out everything before making a purchase in this new world. After you do your homework and narrow things down, I would then come back with those additional questions such as reliability and how a specific device or product works for people. You could easily just pick up the first device someone recommends, but the more you understand what it is you want to accomplish and do that due dilligence, you will be much more happy and satisfied in the end, knowing that you understand everything for yourself and that your purchase is the right one for you and less of a trial and error, because we have all been there.
Thanks @JDRoberts for taking the time. Hope you get to feeling better.
It was a small sample and it is a year old, but it did include the Smartthings sensor which I believe is zigbee. I any case, it is nearly impossible to give an definitive answer as to which sensor is best given each users individual needs and requirements.
Good point, actually thought you were referring to a different three sensor sample. My bad. 
This is very very true. That’s why to me, home automation is like going back to high school. You have to do your home work before trying to ace the test.
As you know, this is a frequent question. I recall a poll regarding these type of sensors was conducted once. Honestly, I don’t know how you remember all the past posts the way you do. We are all lucky for the assistance you provide. Hope you feel better soon.
I don’t have a perfect photographic memory (my sister nearly does), but I do mostly remember what I read. So it’s pretty easy for me, especially if things are filed in the right categories so I can find them again.
As for getting better, that’s not really the way it works. I have good days and bad days, pretty much at random. I appreciate the thought in any case.
For me personally, I take “cheap” and “budget” out of the equation when choosing a specific device. “Cheap” doesn’t always mean flaky and unreliable, but from my experience, you get what you pay for, more times than not. If something is too expensive, I would rather be without the technology for the time being, instead of purchasing something that wasn’t up to par just because it was more affordable than the proven more expensive model to come home later and find out that it doesn’t work, broke, went offline, batteries drained in a day, etc. etc. Sometimes going without it is so much better than the pain that comes with something that doesn’t work the way you expected it to no matter what you paid for it.
This of course is only one thing that I factor in when making a decision for my smart home and it’s not always/only about the price. You will find things that everyone touts and raves about, only to find out that in your environment it didn’t have the same positive results. Some of this is going to be trial and error, as it can be a double edged sword. The best advice I can give before moving forward is that you do your own due diligence and homework and not rely on a single review or post and weigh out all pros and cons and try and mitigate those trial and error situations to a much smaller subset. And if unsure, ask ask ask questions. As you can see from your post today, plenty of people are here to offer their thoughts, suggestions, recommendations.