#4 for me, #5 is just a more diplomatic version of #4 if you ask me, in fact one where you can shift the choice/blame back on to the other band members. If your ideal situation is being in that band with a different singer then don’t p155 about around the edges of that, aim for it. I was a drummer who was usurped in exactly this fashion, the band was better after my replacement stepped in and I have usurped a bass player in the same fashion too, I have remained on good terms with both. I realise this is down to being unbelievably lucky that there were very little ego problems in either band and equally lucky that they were all very reasonable and not inclined to willy wave...
Oh, hang on, I’m an ‘orrible bastard.