This is probably one of the silliest threads on FT, but I have to chime in anyway:

I quite prefer my OP number, probably because I've had it for longer, but it's a really catchy combination with two number pairs and a nice a stair between first pair and second pair (think 11 - 23 - 44). I don't even remember what my MP number looks like, it's just a random string of numbers with some redundant zeros at the beginning!

However, if this were the biggest issue with this merger then I'd be pretty excited...