Go as big as you can afford to go - I went from a 4.5kg machine (and I totally get you on how tiny they are LOL) and doing washing for the 6 of us, to a 9kg top load machine and it's BLISS!!! It actually uses LESS water than my old one because of the way it washes clothes (by taking water out and pumping it back in again over the clothes it doesn't need a full bowl)