This is my choice after a marathon auditioning session at
@Music Sanctuary . I felt that the m3 was the best value of them all. M2 was slightly too warm and smooth for my taste, making it a nice choice for artists choosing a stage monitor that is less fatiguing. M3 was Goldilocks for both value and sound, presenting a more exciting sound, more of a very slight U shape, with (still) very present and enjoyable mids. M4 is the most midcentric, with the most forward vocals, being more of an n shape compared to the m3. I didn't like it as I felt it was not an allrounder enough to be my last iem for the next 5 years. I think vocal lovers will enjoy the heck out of it. The M5 was the m3 on steroids. Way better technicalities and slightly better engagement at the expense of a slightly more recessed midrange. However, I couldn't justify spending that much for an iem at this point of time in my life. In short, if you're on a budget, m3. If price is not an issue, M5 . If M5 miss too recessed, m4. That's all folks xD