Aluminum: Durable, no serious cons unless it's a mac. Macs are overpriced for their computing power.
Plastic: Also durable, just a bit less though. You can get a nicer processor for less if you go the plastic route, and there isn't a big chance of you breaking it over the 3-5 years that you use it if you take the hell care of it.
Answers & Comments
Verified answer
Aluminum: Durable, no serious cons unless it's a mac. Macs are overpriced for their computing power.
Plastic: Also durable, just a bit less though. You can get a nicer processor for less if you go the plastic route, and there isn't a big chance of you breaking it over the 3-5 years that you use it if you take the hell care of it.