There are many good sensors that work with smartthings. Different people have different budgets. For example, The Sensative strips Work well with smartthings, Have great battery life (10 years), are weatherproof, can be painted, and fit in places that other sensors don’t. Zwave plus. But they are much more expensive than most other sensors. So perfect for some people, out of the question for others.
Zigbee sensors Will almost always have better battery life than zwave sensors, and are usually smaller as well. (The Sensative are an exception because they have a patented battery system.) If you are looking for a budget sensor, the Visonic MCT340E zigbee Sensor is popular in the community and works well.
https://www.amazon.com/gp/product/B06XDJ3KYC/
However, before jumping into anything new, I am concerned that you say your iris sensors did not have good battery life, because that brand typically has a reputation as having above average battery life. So it does make me wonder if you have sufficient zigbee repeaters so that your battery operated devices can easily reach the hub and they don’t have to re-transmit the same message three or four times, which obviously uses up 3 to 4 times as much battery life.
This issue is called “mesh strength,“ and generally you should have one zigbee device that can repeat about every 40 to 50 feet in the home. These would normally be plug-in pocket sockets, in wall receptacles, light switches, or IKEA Tradfri lightbulbs.
Because if you have a weak Mesh, that would affect any brand of sensor. 
Also, remember that zwave can repeat only for Z wave and zigbee can repeat only for zigbee, so we are just talking about zigbee devices that use mains power as far as the backbone of your zigbee mesh.
If you’re interested, you can read more about setting up a strong backbone in the following thread. Start with post 11 in that thread, read it, then go back up to the top and read the whole thread.
But if you already have a good zigbee mesh at your house, then there are lots of good sensor choices, you can just look for what’s on sale. Unless, of course, your budget runs to the Sensative strips. 
The smartest House often has some kind of bundle deal on the Sensative strips, so they are worth checking first if you’re interested in that model.