What texting app do ya'll recommend for taking conversations off site? Something that isn't traceable and anonymous. I'm using burner app currently but it doesn't allow videos and some pictures in texts and the VOIP quality isn't the best.

By untraceable?
A lot of apps are encrypted including WhatsApp and even iMessage, but it’s a question of whom you’re hiding from.
If your SO can see your phone or notifications you might be screwed in any case.
A lot of people like Signal, but of course you need the same app your SB is using.

I guess by untraceable I just mean not connected to your cell provider. I suppose being encrypted is another level that can make it hard for the feds to track you? I'm not a tech guy by any stretch so I use these terms generally with limited tech knowledge.

Google voice is good enough 90% of the time.