Do you have much of an idea of where you'll be going? It's tough out of CLT, because US is dominant while United flies one direct route to ORD. The rest are codeshares that they're probably going to lose when US/AA merge and leave *A.

So look at it this way - can Oneworld get you to where you need to go? If so, continue to fly *A now and credit to US. That way you'll get to enjoy the elite benefits when you fly US, as it's pretty hard to go anywhere on another carrier out of CLT.

Another option is to go with United or Aeroplan, knowing you won't be flying either carrier much out of CLT, but you'll have good award availability.

Finally, if you know specifically where you'll be going and know that a foreign carrier like LH is available 100% of the time, you can take the plunge and try them. As you learned, though, they're less generous with full EQM earnings compared to US/UA.

For me, I'd rather have elite benefits than just a bunch of miles somewhere, as I always manage to find a redemption that works. So I stick with US based on the routes I fly out of my home airport.