You're right. This one looks wimpy and too high. I'd go for a thick reclaimed wood look style mantel.

HI -- Your fireplace looks very modern with clean lines . So I think it does not need a mantel . I would remove the molding shelf and live with it for a while and see if you like the tailored no mantel look .... if you don't like it after a while then find a mantel that is more beefy , ... perhaps a metal one or a wood beam , if that is your liking . If you go with a mantel ... make sure it is the width of that wall section and on top of the tile line ..

Remove the mantel completely- it's not in synch with the modern fireplace. I would go without and place a bold large modern art piece above the fireplace.

That is not a mantel. It is a picture molding! So yes, not good. Your surround is pretty so you might be able to paint that "molding" a similar color to your marble (or stone) and then lean a nice piece of art on the wall. Faux paint that shelf to look like honed marble. That would be a quick fix. Remove all the little items and the metal work. Put the metal work on another wall away from that side of the room. Find a great abstract for your fireplace wall. Loads of art out there in all price ranges from World Market for under $200 to real art maybe from an artist on etsy.com. Lots of good options there and many are very reasonable.

Here are some examples from our interior designs that might help you along. Notice all of the mantels, and how each has a painting over the top?

Lake House · More Info

Woodside Model Home · More Info

Open Concept Family Friendly Home · More Info

Take it off and see how you feel about having no mantel for 2 weeks. If you miss it, look around online for something with more heft to it. If you like the modern no-mantel look, you might consider continuing the tile up to the ceiling so the fireplace makes more of a statement.

art listed here:

https://www.etsy.com/listing/463922013/abstract-green-and-blue-canvas-original?ref=shop_home_active_5