By old one I assume you mean the one before this? There have been several logos over the years. They change and evolve overtime. The new one looks more futuristic I think. The one before it was very cool looking as well. I like both but I think I agree I liked the other one better. All personal preference I suppose.
Only the truly old-school will remember the one we launched with:
We moved into a new logo around(ish) the time I joined the team. It updated a couple times from the original rocky texture to cleaner, more modern textures:
We moved on to a personal favorite of mine a while later:
From there, we entered the first period of MANY logos, all at the same time. These weren't all released at the same time, but we use ALL of these and more for various purposes. Sometimes we stop using one, sometimes we add more. Obviously we have one at the top of the site, but it is far from the only logo we use.
My preference? I actually really like the current one at the top of the site. Less edgy, more modern than the previous logos, while still giving a nod to the previous logo.