Need help deciding on equipment!!

Hey everyone,

So, with only a couple of weeks left until we return to school/sixth form/ college etc. I started to look at equipment that I will use next year.
An art teacher suggested that I get a moleskine notebook to jotter down thoughts, I like this idea but I don't actually like the moleskine notebooks.

I want to purchase another brand, called Leuchtturm 1917. They have notebooks in plain, lined, squared, and dotted. In Large, A4, A5, pocket sized and mini. The thing is, my intention is to only use it whenever I get ideas, or want to take a note of something. Not academic.
I don't know if I should get the A5 or the pocket sized. I don't really want to get both.

Here's the link:

Pocket: http://www.thepaperie.co.uk/brands/leuchtturm1917/pocket-notebooks

Medium (A5) : http://www.thepaperie.co.uk/brands/leuchtturm1917/large-notebooks

The pros for the pocket size is that it can easily fit in my jacket pocket, or trouser pocket. So I can carry it around everywhere. It is also small, so I can use it regularly, wherever I am without it seeming obvious
The negs about the pocket size is that it is almost too small. I can't really write in depth notes without running out of space or using loads of pages. I will therefore finish the books faster, and spend more money on more books :/

The pros for the A5, is that it is big enough to write in depth notes and really take advantage of the space available.
The negs about the A5 is that it is too big to fit in my pocket or blazer, so I will only be able to use it if I am carrying my bag with me.

I just wish there was a hybrid between the two! I know it seems a bit silly, but I am really interested in the idea of having a notebook just for jotting down ideas and I want it to be an investment :smile: