I am working to upgrade a couple of HDP clusters from 2.2.9 to 2.6.2, As there is no direct way to upgrade them, I've chosen to upgrade from 2.2 to 2.4 and from 2.4 to 2.6. But there is also the ambari version which has to be taken care of. I've chosen to upgrade from 2.0.2 to 18.104.22.168 (or 22.214.171.124, or 126.96.36.199) and from 188.8.131.52 to 184.108.40.206. What do you think ? Is there a "best" way to chose ?
Yes, Your upgrade Path looks good.
First we need to upgrade Ambari , as Ambari 2.5.2 does not support managing an HDP 2.2 or earlier cluster. So you must first upgrade to HDP 2.3 (you are planning to upgrade to HDP 2.4 first which is good) using Ambari 2.4.2, 2.2.1, 2.2, 2.1 or 2.0 before upgrading to Ambari 2.5.2.
More details about upgrade Path is discussed in the following HCC thread with the Hortonworks doc links:
Good to upgrade ambari 2.4 first then ambari 2.5. I faced problem for ambari upgrase 2.2 to 2.4. SO I took this path 2.2->2.4->2.6