By the time we see the Cloud City in The Empire Strikes Back, it clear that the heroes know that Luke, Leia, and Han have special feelings for each other that go beyond being comrades in the rebellion. Obi-Wan claims that this is the reason why Vader tortures Han and Leia:
BEN: It is you and your abilities the Emperor wants. that is why your friends are made to suffer.
But at that time does Vader1 actually know that Luke is friends2 with Han and Leia?
1 possibly through the Emperor or some other member of the Empire.
2 not just comrades or someone who was conveniently present.
The screenplay of The Empire Strikes Back uses the words "friend/friends/friendly" 23 times, but never by Vader or any other member of the Empire.
Being a secretive organization, the rebellion would try to keep the personal relationships of its members hidden from the Empire. Such information could otherwise be used to compromise people.
The Empire could reasonably assume that Luke would have strong feelings towards any of his comrades.
Leia is an excellent choice as a lure, but for reasons that have nothing to do with friendship. As a leader of the rebellion, any rebel will have strong feelings to protect her. She has also proven to Vader in A New Hope that she is an effective lure for Jedi (Obi-Wan). But these reasons have nothing to do with friendship.
Vader didn't actively choose who would be captured; rather, he took advantage of an opportunity. The capture of the Millenium Falcon is by circumstance (failure of the hyperdrive), rather than by Vader's planning. Similarly, Leia's presence on the Falcon is by circumstance, not by Vader's planning.
If Vader could have chosen a victim to lure Luke, Wedge Antilles would outwardly appear to be a better choice than Han. Both men saved Luke's life in the battle of Yavin. However, Wedge was also Luke's wingman in that battle. In addition, Luke and Wedge are both loyal to the rebellion, Han isn't.
If the answer is "no", then this would once again be a case of Obi-Wan telling Luke things that are "true, from a certain perspective."