What is better- alpine 12" speakers or akoustic 12" speakers - and why?

Well if ya getting the SWS-12 then no but the SWR-12 yes, as for Power Akoustic ive not been a big fan of there stuff and ive been into car audio for over 20+ yrs!

It depends on which particular models you are comparing but its essentially not much difference at the same price levels. The more expensive ones from either manufacturer are not exactly high-end, but they're decent enough and you can also get coil and recone kits for them. At the lower end of the price range their budget models are mediocre at best and are basically throw-aways if they ever need repair. I'd tend to lean toward the Alpines because they've been around a lot longer and have a very good track record with their Type R's. I also prefer the look of the Alpines, but that's ultimately unimportant.

Which sound better to you. They are after all going in your car for you to listen to.

Alpine vs Power Acoustik?

Alpine has 4 different 12's ranging from $60 to $130.
Power Acoustik has 5.

So comparing the two w/o model numbers isn't going to get you anywhere.

In general, alpine is better quality.