In my opinion
No. 1 Laptop
No. 2 PC
No. 3 Tablet
As you all know that you require uninterrupted power supply and internet connection for your trading terminal, charting software, laptop is the best, as no problem of power cut and no internet disconnection, as you will be using data card.
I am using PC for my trading purpose and NOW/Odin as trading platform and amibroker (via Odin) for charting. I am just fed up of using PC.
Though there is no power cut (normally) in our area, but because of slightest disconnection of internet due to minor fluctuation or other reason in power supply, NOW/ODIN stops functioning and so the charting in amibroker (via Odin) and it takes about 4-5 minutes of precious (may be) time to continue.
But in the meantime, the data is poisoned due to non filling of data of this time gap, so the charting values may be wrong due to this. And if there is a power cut (like this week due to grid failure) then only GOD can save.
By using laptop you get rid of these problems. However I may be missing, if there is any problem by using laptop, as I have never used laptop for trading purpose. But spending/investing 30-40K for laptop is an issue for a small trader/investor.