Although I hope to try different sizes in the future, a half size will probably always be my favorite. It is not so large that I can't carry it with me, nor is it too small to hold the information that I like to have close at hand. For someone who loves to make her own inserts, a half-size planner is the perfect size because you can always get two inserts on one letter-size page.
I have never been a big purse person; as a matter of fact, when I get a new purse, I often wonder what I can put in it other than a wallet, keys, and lipstick. Now that I carry a planner, I make sure that it is at least big enough to hold the planner and then .fit the other items around it. A small planner would not work for me at this time during my life because there are a number of things that I need to keep near.
Probably one of the reasons that I have put off trying any other size planner is the fact that creating the inserts would require more work on my part - namely in the cutting of the pages. The personal size planner is what I would like to try next. I have made some inserts for others and have cut them to test them out - it isn't too bad but of course it didn't go as fast as I wanted.
So, room to carry all the things I want is the reason I carry a half-size planner - and let's not forget the fact that half-size inserts allow you to write bigger and more than you would on a smaller size planner - and that's important to me.