If you like badger, don't mess with the boar. You are likely to be disappointed.
I think that 24 mm knots are the sweet spot, but I have brushes from 16 mm (travel brushes) to 30 mm, and enjoy each of them.
Loft is also personal preference. I personally like a lot of loft. Most of my brushes above 20 mm have about 55 mm loft. One of my 30 mm brushes is set at 58 mm loft, and the other one at 69 mm loft. I shaved with the 30/69 this morning. Although it is a bit of a handful, it was very enjoyable. YMMV.
The only way to know is to try it as you can best guess from insight you can gain from others and see for yourself.
Yes...the choice is very subjective and personal. I LOVE a medium sized Omega boar I bought over 3 years ago...it only gets better with age. I like a few badger knots, too. Tony at The Golden Nib sells a couple of boars, including the 23mm knot that matches the one I have...lots of guys swear by boar. It is very soft, very good at making lather in bowl or on face, and gives up lather better than any other brush I have. I think they are underrated. If keeping the brush "original" is cool for you, don't shy away from boar.
Three other very popular knots are TGN's Silvertip Grade A and Finest 2-band, and the Silvertip offered by Larry at The Whipped Dog. I just bought one of Larry's knots for a 200 I am restoring...20mm is about right for the 200s I have. What a NICE badger knot it is! You will probably enjoy any of these knots.
Also realize that you will probably restore more handles...the obsession burns deep, my friend! So...pick a knot and then try a different one in your next handle. My goal is to have 3 restores---handles I love, one in boar, one badger, and a good nylon brush. (I love the TGN nylon I have in a 200 right now...it's a beauty that performs very well.