Spoiler
Normally, it's correct to take a checker off. With an odd number of checkers off, taking off only one is not as useful since it doesn't save a roll. 6/3 4/2 means we won't have any gaps, so that play should at least be considered.
But I'm going to go with taking one off - after 6/3 4/2 we'll need to take off two every roll to stay ahead of the game and I expect at least one miss.
So, 1/off, and then do we play the 3 from the 6, 5, or 4? 5/2 unstacks and fills in a gap. 6/3 just fills a gap. 4/1 does neither.
I'll go with 5/2.
Spoiler
1 off, then for the 3 i'd move 5-2. that helps unstack our largest stack, fills in the gap on the 2 and leaves an even #of checkers on the 5.