In terms of how well you want to perform, you should definitely choose Advanced. In Advanced English it is aligned better so it is much easier t get a Band 6 or even a band 5 compared to Standard. It should be also worth noting that based on something I recall reading, the median mark for Standard last year was 68 while the median mark for Advanced was 81. Overall, Advanced is the best option for you, regardless of skill.
Hope this helps