I'm always looking for new sketch brushes to give different feelings to my sketches, so here's some I enjoyed that I'd like to share with you. :)

I encourage you to modify the settings of the brushes to your liking.  The most important part of a sketch pen is that it is comfortable to you!  And if you don't like them at all, feel free to delete them. c:

The Sketchers in detail:
Icelandic Sketcher - Has nothing to do with Iceland, just what I drew for the preview and thought it would be a nice name.  ^^;  It's a marker pen that is fluffy and light at large sizes, and dense and precise at small sizes.  It is great for shading.

Color dip - This one is a fun chisel tipped marker that changes color the more pressure you put on it.  Feel free to adjust how much it changes or if it changes at all :0.  It gives a nice flair to general sketches.

Trouble maker sketcher - a marker that has a little divot in it, giving a bisected line.  It gives crisp dark lines for more final sketches and is fun to do hatching with.
Mindless Sketcher - an airbrush sketcher.  I like to use it at small sizes (this was 4px) & build lines up gradually with it.  Size by pressure is turned OFF by default to focus on density & opacity by pressure, but adjust it to your liking.  It is very soft and is good for shading at large sizes.

Groovy Sketcher - another one made for fuh, made with a texture that is full of grooves & bumps.  It has color jitter on for extra fun :D
Starstruck Sketcher - The tip is a pixel star that rotates into random angles for a fuzzy effect.  Good for those who are more comfortable with a messy line for their sketches.
Staircase Sketcher - I don't know how this got into my brushes.  I think I had a tip but deleted it and just kept the brush anyway since the settings (the opacity pressure control looks like a staircase) worked pretty alright for sketching.  So hopefully you can find a use for it, but if not, feel free to delete it if it doesn't work.

Sketch and Paint - A rectangular flat brush with a ribbon type stroke. Great for speedpaints.
Glide sketch - this one has tilt control on for it's thickness size, so if your tablet cannot do tilt feel free to turn it off.  It is thick on low pressure, thinner on medium pressure, and thick again on full pressure.  It feels good to run across the canvas on light pressure thanks to it.  It is another good one to use for speedpaints as the colors blend. 

Square Sketch - A fuzzy square tip that is tilted at an angle.  It makes good corners thanks to its shape, and can make some very smooth lines.

Lastly, here's basic lines and shapes made with them to demonstrait how they work and how the brush looks overlapped with itself.

Glide Sketch:

Sketch & Paint:
Trouble Maker:
Color Dip: