I have both, and I don't really have a preference. But the Zefal is at least 20 years old and still works like new. The Topeak is probably four or five, but hasn't been used much, so I can't judge reliability. And while I don't consider appearance when I'm choosing stuff like that, the Zefal does look pretty cool under the top tube.
Speaking of Silcas, I bought one years ago because all the cool guys in my area used them. The first time I put it on a tire, the piston slammed back and hit me in the face and the barrel exploded into half a dozen pieces. I've heard since that there's a technique to using them, but I don't know what it is.