Ive tried the PT3 vs. Aspire for about a month, using only those two.
PT3 pros : fully disassemble-able, great flavor, no leaking/gurgling, heads last a while.
PT3 cons : Vapor is so-so (but still good).
Aspire pros : Excellent vapor, excellent flavor.
Aspire cons : Harder to fully clean in between flavors, had several issues with gurgling, heads have been very problematic- some have lasted me only 10 minutes!!
Cheapest ive seen for heads is $7.99 for 5 PT3 heads, $9.99 for 5 aspire heads.
Ill always have both, but im using PT3 90% of the time. Its just easy and maintenance free, just works. When I take the Aspire outside the house, im always worried my coil may decide to go to pot.
They BOTH suck up a lot of juice BTW.
One thing to be very aware of- you MUST run these at higher voltages than you would vs a single coil. For example, with the 2ohm PT3 heads, you need to set your voltage as if you have ONE FOUR OHM coil. If you run too low, then you will slow-boil your juice on the head and create lots of gunk quickly. Id run the PT3 over 4.2V, and the Aspire 2.2ohm over 4.5V.