I would vote for the larger one just for the ease of entry and it gives you some extra space to carry self rescue loops etc., in the bottom. I actually prefer having my ropes and other immediate access stuff like my gps, water bottle, pull down line, madrock/biner, self rescue loops/utility knife in dump pouches so that they are either immediately available while I’m walking in or immediately available if I find myself hanging upside down from a rope on the side of the tree vice uselessly hanging in a backpack on the side of the tree several feet above my head.
I’ve never had a problem with the weight on my saddle and in fact I like it because it distributes the weight nicely around my body and on my hips, vs. all of it on my back in a backpack, although a good hipbelt solves most of that for a pack. Also don’t like a pack sweating up my back. Many will disagree because they can’t keep their saddle around their waist or they feel it limits their movement in the tree. Never been an issue for me. I walk in over a mile and hang in the tree with them and never even know they are there. So, it really comes down to you and how you like to manage things. There are several different ways to do it, no right or wrong, and only you know what you like. Good Luck!