Is one use more common, or does each have a different nuance?

見たこと有る。More of a possession nuance.

でかいテレビも在る。More of an existence nuance.

Although note that ある is most commonly written in hiragana.

And note furthermore than when 有る and 在る appear in modern Japanese, it's usually because the typist is ワープロ馬鹿 and likes to use the IME to get as many kanji as possible. So I strongly recommend against using them.

- Kef