Orientation of lot

OP, I congratulate you for considering orientation at this early stage. Most people don't consider it at all, or consider it once they've already purchased a block, which may make it much tougher to come up with a comfortable, thermally efficient design.

Have a read of this very useful government site. It will explain orientation, & how to design a thermally efficient home. There's quite a bit of detail there, if you want to sink your teeth into it. I recommend that you do, as the more educated you are, the better the chances that you'll end up with a very well design home, that is not only comfortable, but cheap to run.

http://yourhome.gov.au/passive-design/orientation

To summarize all of this. For our climate the best shaped house is rectangular. With the longer sides facing north & south (the long northern side receiving plentiful winter sunshine). Shorter sides to the east & west (the shorter western side receiving less hot afternoon summer sunshine). You want your living areas (& a high proportion of your glazing to face north). Your home will then be heated by the sun in winter (when the sun is lower in the northern sky), & shaded in summer (when the sun is higher in the northern sky). This is called "passive solar design".

Both orientations you've listed can be great, but only in the right circumstances. Generally, with everything else being considered equal, as others have mentioned the south facing frontage would be the pick. But this is not always the case. The frontage must be a respectable size (so you can have a good deal of north facing glazing out back, where you'd locate your living areas). You also won't want a large covered alfresco area out back in this orientation. As it will shade the home, making it darker year-round, & colder in winter. Your rear garden will get ample sunshine in this orientation, no matter what you do.

A western frontage can also be good with the right block. But usually it has to be a wide block, so that northern windows are not shaded by the northern neighbour's house. It's recommended to build close to the southern boundary, leaving a larger northern side yard, to prevent overshadowing from your northern neighbour. This orientation can actually produce a more efficient passive solar home than a southern frontage orientation. This is because it's easier to get the house shape right, with large northern & southern faces, & smaller eastern & western faces. Another advantage is that the garage (which is usually a large double garage nowadays), will face west. Protecting the house from harsh afternoon summer sun. A nice wide porch at the front will also help protect the home from afternoon sunshine. A master bedroom at the front isn't a good idea, as it can be very badly effected by this hot afternoon summer sun. A covered alfresco area can face east, out the back. This will help shade the home on summer mornings, but will not inhibit winter northern sunshine from entering the home. But, like all passive house designs in the southern hemisphere, you want your living areas (& a large proportion of your windows) facing north. Which happens to be straight towards your northern neighbour in many cases, creating major privacy issues!

So each case is different. A western frontage can be great, where overshadowing & privacy are not a concern. Often wide blocks, & steeply sloping blocks (sloping down towards the north - so you can look over the top of your northern neighbour, & not be overshadowed by them) are best. But these blocks aren't that common.

So generally, a nice wide southern frontage is best. Bedrooms facing south & east, very few western windows (bathrooms & laundries), garage on the western side, with north facing living areas facing out back.

Obviously, the fact that the southern frontage lot is in a quieter location is a huge plus for it as well.

As par vastu, south one is least preferred, although entrance gate can be shifted to fix it if interested to go for south facing.