I've always used SMB 1.0 for many years, before I noticed V2 was an option to enforce on my RT-AC66U_B1. My clients are 2 Android 9.0 (FireTV) with Kodi 18.9 and a Windows 11 machine with Kodi 19.3. Mostly for streaming video files. I haven't had a problem but wanted to see what everyone else used. NFS V3 on Merlin looks so-so, it would probably be a slam dunk if it were V4 and thus stateless. So for now I've been sticking with SMB V2.