I used a laptop and still do for mobile applications. (intel I5 / 8 GB ram)
however when all possible, I prefer a desktop to any laptop out there for a few reasons.
cooling is one, expansion is another. power consumption doesn't seem to be spared on desktops as much as laptops.
Ive also found Intel's naming nomenclature leaves a lot to be desired when comparing desktop to mobile CPUs. Looking at Haswell CPUs:
Desktop i3 = 2 cores, 3-4 MB cache, hyperthreading, no turbo boost
Desktop i5 = 4 cores (mostly), 6 MB cache, no hyperthreading, turbo boost
Desktop i7 = 4 cores, 8 MB cache, hyperthreading, turbo boost
Mobile i3 = 2 cores, 3 MB cache, hyperthreading, no turbo boost
Mobile i5 = 2 cores, 3 MB cache, hyperthreading, turbo boost
Mobile i7 = 2 cores/4 MB cache, or 4 cores/6-8 MB cache, hyperthreading, turbo boost
There are slight differences in features too, but the above are the major performance enhancements. The other thing you can't see in the above is that the desktop processors tend to be clocked higher (and have higher power consumption as a consequence).
over all, Expansion.
you can expand so much more on a desktop than a laptop.
I wont even get in to repairs. just putting it lightly...Desktops are much easier to work with upgrade.