I'm in year 10 and I take both subjects - if you prefer tests, then take Geography - if you prefer writing essays then take History. However, I would say that the Geography course is more versatile.
History is 4 modules (Vietnam War, Medicine, post-1945 Germany and Surgery) worth 25% each that you write some essays on.
I'm not sure how many modules of Geography there are, but I know that there's human geography and physical geography and then the field work that you do, but it is a mixture of tests, essays and decision making (evaluative) papers.
Honestly, I would suggest taking both subjects, but if you can't then I would say think about which one you enjoy more, what format of examination you prefer (test/essay), and which one you're better at. Lots of teachers tell us that a history GCSE is seen as more prestige than a Geography GCSE, but if you do take Geography, then a good grade in English Lit will make up for it, as history measures your writing skill.
Geography is easier however - you are given lots of case studies to remember, and questions in the exam about case studies are worth quite a few marks. History exams are more about making inferences on the spot, and there is a lot more to remember
Whichever one you choose, I'm sure you'll do fine