I'm definitely going to buy the official wristband, the timetable on the student union website for all the wristband events looks pretty good and I'd assume that's what most people are going to go to. I might also get one of the moving in party tickets. I'm not getting any of the unofficial freshers tickets or wristbands though, they seem kinda scammy
From my friends, we are in our 2nd and final year, the wristband is useful but overall if you arent interested in attending all the parties it may be inefficient price wise since you can also queue on the door to buy some. Although there is no gurantee of getting in. I hope this helps.