Kind of comes down to personal preference and physical build, as stride length/height/leg length plays a role.
If you aren't sure, take two of your existing climbing sticks and head out to a tree with a tape measure.
Put on your heaviest/bulky layers that you'd use when hunting.
Do two tests - space your existing climbing sticks out 22" apart and 18" apart (which is the step distance for the 24" and 20" beast sticks), and see which one fits you better.
If you are 6'2" tall, more than likely you will be fine with the 24" standard beast sticks, but you can figure it out before ordering with what I've described above.
If you are buying 5 sticks, the 24" standard sticks will get you 20" higher off the ground than the 20" mini sticks. (22"-18")*5 = 20", or 1'8"