I think @HappilyExperimenting has tried a couple of them...I'm sure I've seen reviews from her on the product pages.
Hopefully she'll creep up and be able to offer you some advice, or someone else too. :)
Hellooo, here I am! 
I have tried two Happy Rabbits - the Natural and the G-Spot. I really dig g-spot toys now, they're my favourite. I found the Happy Rabbit Natural not stimulating enough to hit my pleasure points, you see. But it's all different for different individuals so I can't reccommend a specific rabbit for you missyelle.
I do reccommend that you don't jump in the deep end with a rabbit though - if you prefer slimline toys none of the Happy Rabbits may suit you. Just go with your gut instinct (not your favourite colour!) and check out the measurements for the Happy Rabbits first - some are girthier than others, or longer. LH have a fantastic returns policy if you need to exchange one Happy Rabbit for another and it's so easy to use!
Good luck and happy shopping!
I agree, definitely don't go with your favourite colour this time! That's how I ended up with the Happy Rabbit G-spot which had to be sent back because it was just too big and not stimulating enough. I wanted to like it, I really wanted to like it but it just wasn't meant to be.
If this is your first Rabbit I'd recommend this instead: http://www.lovehoney.co.uk/product.cfm?p=22191 more powerful than the Happy Rabbit G-spot and considerably smaller. The silicone is so much nicer too, I found that the ears on the happy rabbit were too painful whereas the Oh! Rabbit feels incredible.
The Oh! Rabbits are in a different league to the Happy Rabbits, but not in a bad way. Oh! Rabbits take batteries and are a bit louder, but attract less dust and fluff than a Happy Rabbit. They are also cheaper and the ears are more rounded. Happy Rabbits tend to have sharper ears, as PPD has said. I would recommend an Oh! Rabbit as well; I have the Slimline and the Realistic and prefer the former if I'm being honest.
But at the end of the day it is up to you and nobody knows you better than yourself! :)