In need of new pump, looking for advise!

[The Raddish]

We currently have an Astral pools 1hp pump that is on its last leg. I have been looking at the pump I mentioned above, along with three others.

Hayward Max-Flo Pool Pump ( Max Rated) | .5hp - HAYSP2800X5
Hayward Northstar Pool Pump Energy Efficient | .5hp - HAYSP4005NS
Hayward Power Flo II Above Ground Pool Pump | .5hp - SP1750

Money really isn't an issue, and I'm leaning toward the Northstar due to its claim of energy efficiency and quietness, but I'd like to get an opinion on the three pumps as well as the one recommended by Ben which is getting increasingly more difficult to find (always a concern when a product approaches the end of its life cycle).

HAYWARD SUPER PUMP MAX RATED 1/2 HP 115V

I haven't even considered looking at anything other than Hayward, but I suppose opening my options up a bit isn't a bad idea. I'll take a look at the Pentair 3/4 HP Dynamo 2 Speed Pump as you suggested.

I'd like to know what pump I'm going to be buying in case the Astral doesn't make it through the season. I guess I want to have my research done so I can pull the trigger quickly if needed.

[jenpen400]

I found a lot of great info here http://www.poolplaza.com/C-Pool-Pumps.html Each pool is different. They explain how to determine turn over rates, total dynamic head, maximum flo rates for the filter and how to read pump curves. Once you find out the particulars on your pool then you look over the pump curves and find out which pump best suits your needs. Too much power and you waste energy and your filter is less effective. Two speed pumps are great because they give you both efficiency and power when you need to backwash and vacuum.

Jennifer