I don't exactly have a favourite xyzzy, but I do think 5 is a very cosy, comforting number. No intellectual reason - it just crops up in all my families birth dates.
Apparently, when asked to choose a favourite number, most people will choose 7. David Beckham has apparently chosen the number 23 at his new club because he thinks that 2 + 3 = 7.
23 is a good number for me, my birthday and my sons (the most ridiculously easy birth ever) and its generally been a lucky number for me. other numbers are just as lucky but i dont notice them because they are not as memorable as 23. it is beckham's new number which may be is lucky, but its also the number marc vivien foe was wearing when he dropped dead for no reason. you be the judge, i hope you lucky number is lucky for you.
13, it's also supposed to be my lucky number, never had a bad Friday the 13th so far but I think it also appeals to the perverse streak in my nature. Also suffer from a 5 fetish
aha, 142857, the decimal reciprocal of 1/7; cyclical patterns are in the number; unless you times it by 7, then you get 999,999 how cool is that for a boring looking number? also, if you split 142857 in half, 142+857 = 999, and in pairs, 14+28+57=99, and is the number prime? no, because if you divide it by 143 you get 999 again, spooky. :-)
8 as its even and is low so its a 'nice' number to me. Is also the door number of the house I grew up in, the flat number of my uncle, when I met my boyfriend he lived in Flat 8, and his mum lived in house number 8 - it just keeps cropping up for me.