Whether to go for a 13" or 15" Macbook Pro really depends on your needs. I currently have a (at the moment
broken) early-2008 15" MBP (with a matte screen), but have used friends' recent unibody 13" and 15" MBPs (including both normal glossy and hi-res matte versions), and also both the 13" and 11" MBA, so have a reasonably good idea of what they're all like.
What I
can tell you are the main differences, but it depends whether these matter to you:
15" MBP Pros:
* Bigger screen (obviously...)
* Higher resolution standard screen (1440 x 900) than 13" MBP (1280 x 800)
* Hi-res screen options (1680 x 1050)
* Matte screen (hi-res) option - important if you hate reflections (like me) or need to have accurate colour reproduction e.g. if doing lots of work in Photoshop, then this could be crucial
* Quad core processors (vs. dual core on 13") on all models
* Dedicated graphics processor (though only the more expensive AMD 6750 one is much good, if you you want to play modern 3D games)
* Seperate Audio line in/line out (though if you really care about studio-quality audio recording etc. you would probably have an external Firewire audio interface)
* Better sound quality from the built-in speakers - though if you want hi-fi sound you should plug-in some good headphones or into a proper amplifier/speaker setup
15" MBP Cons:
* More expensive (especially so if you go for the model with the AMD 6750 graphics and choose a hi-res screen option)
* Physically larger (obviously, but then you are getting a bigger screen), though will easily fit in most backpacks, cycle panniers etc.
* Heavier (5.6 pounds / 2.54 kg) - though the matte screen version is slightly lighter, as doesn't have a glass screen
*
SATA III 6Gb/s speeds not possible in optibay (if swapping out superdrive for an SSD and want to put the in the optibay instead of the HDD bay). Current model is fitted for SATA III in optibay, but this only works properly on the 13" model, for some bizarre reason - more info.
here
13" MBP Pros:
* Lighter (4.5 pounds / 2.04 kg)
* Smaller footprint - better for use on planes, trains etc. and easier to carry
*
Optibay works properly with SATAIII 6Gb/s if you want to swap out the superdrive and install an SSD there (though I still think its better to have the boot drive SSD in the HDD bay)
* Cheaper
13" MBP Cons:
* Smaller screen
* Lower screen resolution (1280 x 800) than standard 15" MBP screen option (and lower res than 13" MBA, which is 1440 x 900)
* No hi-res screen option
* No matte-screen option
* No seperate audio in/out (though does support both through a dual in/out socket)
* No dedicated graphics processor available
* Only dual-core (as opposed to quad-core) CPUs available
* Sounds quality from built-in speakers not as good
I think that about covers it, apart from perhaps
aesthetics - the 13" model is perhaps more cute-looking, but they're both damn-fine looking designs IMHO.
For me the 15" model is best and if I was to replace my current early-2008 MBP I would still go for this size.
As for the differences between the 13" Macbook Air and the 13" Macbook Pro.
13" MBA Pros:
* Much thinner!
* Much lighter! (2.96 pounds / 1.35 kg)
* Very cute aesthetics and "wow!" factor
* Higher-resolution screen (1440 x 900)
* Bluetooth 4.0 wireless technology (current early-2011 MBPs have Bluetooth 2.1 + HDR)
13" MBA Cons:
* Can't upgrade RAM at all, 4Gb max RAM (MBP officially support 8Gb RAM, though I think its possible to upgrade to 16Gb, though this is still vry expensive)
* Can't easily (or cheaply) upgrade the SSD
* No superdrive DVD recorder (though you can buy an external one)
* No room for a second HDD or SSD (in the MBP you can swap out the Superdrive for a second HDD or SSD with an adaptor). In a MBP you can have a fast SSD for the OS and apps, and a high-capacity HDD in the optibay for storage (music, movies)
* More expensive (though not by a lot) for a similarly equiped MBP, assuming you bought a third-party SSD for the MBP rather than pay Apple a fortune for their upgrade.
* Slower CPUs (best is the dual-core 1.8GHz Intel Core i7 as a BTO option)
* No Firewire port (a big issue for me, as have a Firewire audio interface, as well as a number of external Firewire 400 and 800 drives)
* Facetime camera is not HD (may only an issue if you use Facetime or Skype alot)
* Keyboard does not have as nice "feel" (less travel, I think)
* No Kensington lock slot - don't leave it lying around in public!
* Built-in speakers sound worse than 13" MBP
*
EDIT: No ethernet socket
If money wasn't an issue (which it is, unfortunately) what I would actually like in an ideal world would be a 15" MBP for home/office and an 11" MBP for travel...
