It all comes down to whether you want to stay in the US or not.
- If you want to stay in the US, go for Tuck, I also understand that they've completed the STEM certification, so a clear winner there.
- If you want to work in EU, ME or Asia, go for LBS.
Going from LBS to the US will be a pain, but on the flipside they have a bigger footprint in other geographies. If you're undecided, I'd possibly choose Tuck, as you might have more options carrying the Dartmouth brand to the places LBS is definitely stronger.
They are similar schools in terms of prestige, so it shouldn't be a deciding factor. Plus it's hard to get a definitive answer, as most of us in this forum have biases depending on whether we look at it from a US or EU B-school perspective.
Best of luck!