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It really depends on what you will be using it for. I think that the Conn is a better all around horn because of the bigger bell. The Werils that I tried are decent horns, but I couldn't get the kind of projection from them that I could from a Conn 5J. If you are looking for something lightweight, or for small ensembles, then the Weril is a reasonable choice. Unless it is a Mexi-Conn, I would expect the Conn to be slightly sturdier.

Bottom line, they're both tubas.

If portability is the issue then get the Weril.
If sound is the issue then get the Conn.
The two instruments are different enough so that you should have no trouble deciding which works better for you if you try them both. Why ask anyone else?