Oooh good question. Ok, let's think.
I think each album is amazing and has it's own amazing tracks and my opinion does tend to change every time I listen to them so here goes.
1.Origin Of Symmetry- This was the album that got me into them so it has that special place in my heart. Stand-out track are Bliss, Plug In Baby, Space Dementia and Citizen Erased.
2. Absolution- This album is out of this world amazing. Love the fact that there's a lot of piano tracks in it. Stand-out tracks are Apocalypse Please, Stockhom Syndrome, Hysteria and The Small Print.
3. Black Holes And Revelations- I love this album but I think it's too early to rate it any higher. I need to wait a while to see it it'll pass the test of time. I'm sure it could well overtake the other albums given time. Stand-out tracks are Map Of The Problematique, Assassin, Knights Of Cydonia and City Of Delusion.
4. Showbiz- This album is fantastic but in comparison to the others it sounds like Muse are just finding their feet at this point. For me, Origin is where they became gods...but this is a good, solid foundation. Stand-out tracks are Sunburn, Fillip, Overdue and Hate This And I'll Love You.
Hullaballoo for me is not considered an actual album...like someone else said, it's like a special treat for fans. I love it though.
My opinions are likely to change the moment I post this though.
xx