I live in the US but fly to Europe perhaps 3-4 times/year. I'm usually required to book a flight on UA or a code share, which means either UA or LH in practice for my routes. I think that the service on LH is far better than that on UA, so I almost always pick LH for these flights.

Would it be better to maintain my UA status (only Premier this year), or should I switch over to LH? I'm mostly interested in getting upgrades for the long-haul flights. I usually fly on Y class tix.

Thanks in advance for any advice.