Are looking for something that sounds different or something very similar to the A90?
Not knowing someone's preference, system, room acoustics, etc., makes it hard to make a specific recommendation. All I can say is that I've heard both (I own a Titan), and both are really fine cartridges that can deliver terrific sound. There are certainly a lot of other cartridges that would be contenders too. I personally like the Transfiguration Orheus L (I own that one too), and I have heard great sounding systems that use Allaerte cartridges. Of my two cartridges, I really cannot say which I prefer. In my system, the slightly more prominent upper midrange of the Orpheus is a plus, but, I like the beautifully open and extended sound of the Titan too. I suppose that, if I had to pick one, it would be the Titan.
I haven't done much direct comparisons of cartridges myself. In a friend's system, we once did direct comparisons involving two arms (Phantom and Vector IV) on a single table. Two of my friends preferred the Orpheus to the Titan with either arm (I marginally preferred the Orpheus).
In Stereophile magazine, Michael Fremer wrote about making digital copies of the A90 and the Orpheus playing the same tracks which he then played on various systems at shows. He reported that the majority of listeners preferred the Orpheus (for what that is worth).