AV
To me the AV question is no brainer.
Not because it is fairer that's a far too complex question. Not because it stops tactical voting (it won't) or because it leads to coalitions (who knows if it will or if they are good or bad). What it will do is lead each MP to consider, just a little bit more, every member of their constituency not just their core voters. Like everyone else they pay most attention to the people they meet on a regular basis which is members of their party and other MPs. This will give them a small reason to think of everyone, at least near elections, and as someone who does not think like an MP I feel this is a good thing.
Not because it is fairer that's a far too complex question. Not because it stops tactical voting (it won't) or because it leads to coalitions (who knows if it will or if they are good or bad). What it will do is lead each MP to consider, just a little bit more, every member of their constituency not just their core voters. Like everyone else they pay most attention to the people they meet on a regular basis which is members of their party and other MPs. This will give them a small reason to think of everyone, at least near elections, and as someone who does not think like an MP I feel this is a good thing.