It depends on how much you like science. For triple you learn a little more in depth for each of the three sciences, however the difference isn't massive. I always recommend triple because I like science, but again it's personal preference.
In terms of studying for it, the CGP revision guides are amazing for the content, and you will also want to closely follow the specifications. I also recommend physics and maths tutor for practise questions, although I am not sure how their GCSE stuff is as I've only ever used it for A-Levels. Freesciencelessons is also a really good youtube channel that explains triple content.
I also recommend anki, it's brilliant for remembering content and for recalling it. To download it on laptop/mac/Android it's free but the IOS app costs £23 (to support the developers). Although if you have a laptop, you won't need the app anyways! Its user interface may seem a bit scary at first, but you'll soon get use to it! There are also many anki tutorial yt videos too.