Personal picks for cast of Harry Potter?

I always had Jeremy Irons in my mind for Snape, Rufus Sewell or Ben Chaplin could have done Sirius, but they don't feel quite right either. Think Alison Steadman would have made a great Professor Trelawny. I always had David Thewlis in my mind's eye for Lupin when I read the books, but was a little dissappointed in the performance when I saw the films, think Tim Roth would have been a better choice.