Probably Gale. Due to the dark urge path. I don't hate him and he is nice and easy to please but it will set a darker tone to the adventure. Now if there is a second chance to recruit him, I will do so.
But yeah, with the dark urge nobody is safe.
But I will try my best to rein some of the urges to keep the others. I genuinely enjoy SH and Astarion, so I do hope they will survive to the end.
Personally, I find Lae'zel annoying but one companion less is already a hit. I can't afford losing more, esp. with the unpredictable stuff that can happen.
As for Halsin vs. Minthara, in EA I stuck with the tieflings. But I am going for a very chaotic run (though I won't go ultra-evil), so anything is possible.
