Oober is right. It depends on your location, situation, and number of searchers in your region. That said, I'll give my experience. I'm sure I've searched over $100k in dimes and hundreds of thousands in halves. If you like the satisfaction of finding silver on every hunt, dimes are way more consistent. Although in my region, picking the right courier is a must(this is not typical). Halves are hit and miss but the silver per amount searched is at least twice as good.
For the record, if I would have began halves during a skunk streak, I would have never figured out that halves were so good. I would have quit before reaching a 10 box skunk streak. I've had several.