I couldn't choose who to have as my best man out of my best mates (2 were in the running), my brothers (I have five of them, though only one is a realistic choice), my nephew (well, my oldest nephew) and my dad.
I had previously asked one of my best mates in a drunken stupor some years ago but now that I'm actually getting married I decided to have one of my brothers, my oldest nephew and my two best mates all as groomsmen, with one of my mates from the party giving the speech. The wife's having 4 bridesmaids anyway so it'll be even this way and saves me having to choose between them.
I did make sure I picked the best speaker of the lot for the speech though