Cornerbog

I'm about to start my second build (technically first cause everything is being bought by me) with a Obsidian 450D and I want to get some good quality fans, preferably RGB than one standard colour. My question is though, which fan should I buy?! :eek::sigh!: I don't really know the difference between all the AF, SP, HD, ML and LL fans, so I don't know which I should get for my AIO fans and my case fans. Any help would be massively appreciated. :D: :biggrin: