I'm setting up a SRX340 cluster for a branch office and I don't like the idea of take it to production with the JTAC Recommended Junos Software Version, which is Junos 15.1X49-D170, because it's end of support in a few months ahead, in May 2020. I can't understand why there are 13 (!!!) newer Junos versions but Juniper don't consider any of them stable enough to recommend it, while they keep releasing more and more new versions.
I'd like to upgrade these firewalls now with a Junos version which end of support was, at least, 2021.
In the light of your experience, which Junos version above 18.1 would you recommend? I mean, any that you have tried and tested, and you are aware is working fine.
Firstly I would like to inform you that the recommended Junos versions are selected using input from Juniper Engineering, customers, and analysis of field usage data.
Currently, we don't have any information regarding the next recommended Junos version for SRX300 series devices. However, I reckon Junos 18.4 will be made as recommended release as it is the last release from the Juniper in 18.x train.
So, I would suggest you upgrade the device to Junos 18.4R2 which is the most recent release. On the other hand, Juniper made Junos 18.2R2 as the recommended release for the SRX5k series line and SRX4600.