STRESSED. dad says my SISTER & I must CHOOSE within 10 DAYS. Its a VERY STRESSFUL situation. Please help?

I'm so totally pissed off. My sister and I are 20yrs old and 19yrs old respectively. In September my sister and I will be moving out of our family home and our father is purchasing a start up property for us, which we may sell after a few years and split the profit and then put the money towards larger properties for each of us. However, my sister, (19) and I cannot agree on this. We have the choice between a 3 bed luxury apartment or a 2 bed penthouse which obviously has generous outside space. I like the idea of plenty outside space especially in the centre of the city. My sister wants to settle for the smallish balcony of the 3 bed and have spare room. The 2 bed penthouse has oodles of space, the rooms are very spacious and the living room area will easily cater for any guests. Now my father has brought us to see another property, this time a house (4 bedroom) in a lovely suburb, with an ample back garden but it is a good 15 minute walk to the city. We are both so confused. We are both going on one months vacation in 10 days time so we would like to have this settled before we can relax. What will we do. Also daddy is pressuring us to make a choice.