We made the "soft" decision to pursue this course of action a couple of years ago, and as of now we have a hard deadline of year end to completely migrate from our iSeries to a full Windows/MSSQL environment. One of the most helpful things we did early on (in 2019) was make the decision to stand up a Windows ES with our DV920 pathcode installed on it, and hook it in to our iSeries DB in addition to our iSeries ES. This allowed us to get a better understanding of how the "basic" windows side of things works compared to iSeries (job queues, JDE services, printing, fonts, 3rd party apps, etc etc etc). A lot of the decisions you're going to have to make in regards to "what's best for you" is generally strictly based on your organization needs and staffing. For example, one of the big hangups we had in our environment was that over the years (since we implemented Oneworld in the late 90's) was that we had grown incredibly reliant on iSeries CL/RPG programs to supplement our business processes. Having that windows enterprise server in place in dev allowed us to really test a lot of proof of concepts using that platform and implement platform agnostic processes, so that now the only step left is to migrate our business data to SQL. As a side/main note, we are planning on a migration within the same version/bitness (our iSeries platform is on 9.2.6.3 UN6, as is our newly minted Windows/SQL platform).
Again, I don't know if there is any true one size fits all approach, but that is what we did, and it has worked well for us thus far.