I’ve seen a couple other posts on this topic, but the replies didn’t touch on the things that I’m concerned about. One thing that I’ve picked up is that the Horizon is over-sized but amazing at finger-spins. People have said that the spin time is great and it’s extremely stable, but I’m worried about its size being awkward/uncomfortable in my hand. My hands are a tad bit smaller than average and I’ve never thrown an over-sized yoyo so that may pose a small conflict. The Shutter on the other hand is really popular and people have said that it’s good for just about everything, but I’ve also read that it isn’t as stable as other yoyos, which worries me as a pretty sloppy yoyoer. In your own opinion, which yoyo would be the best for me?
Shutter is very stable so don’t worry about that, but the size of the horizon isn’t that bad. I have small hands as well but I liked it. You could be different though.
http://yoyoexpert.com/forums/index.php/topic,78587.0.html
The above topic covered this exact subject and has a lot of good information in it. I’ve posted up a rather long post on the subject on page 2 so there’s no need to repeat myself here. 
Really they’re both great throws and either will serve you well, so you just need to look at the stats and shape of both and decide what one you think you’ll enjoy more. If the slightly larger size of the Horizon bothers you then you won’t be missing out by going for the Shutter instead.
Also I have no issues with the stability of the Shutter. It’s not going to win an award for it, but it’s more than sufficient for everything I’ve thrown at it. 
Well lets see
Shutter is so well known and so many people have had a good experience with it, its a safe haven.
I was skeptical of the Horizon at first but as soon as it arrived, I enjoyed it a lot. It is an oversized throw and that can interfere with something like chopsticks mounts or something like that.
Its hard to go wrong with either, its just preference, compare the specs and decide from there.