I will start with the worst ones...
This is Craftsmart by Michael's. One time I came across one that really worked well, but lately I bought two that are AWFUL. You push the nib down and expect to get a good flow, but you get a huge blob and no flow. I'm taking them back. They were $3.99 or $3.49 (can't recall exactly.) This pen does not work well on canvas either if you're trying to outline something.
You would think Prismacolor would have a great pen, but this does not work on paper, or any other surface. Just don't buy it.
Pen-touch by Sakura. It's goes on in blobs and it's hard to use. I regret buying that one, and I don't remember the price.
Gelli Roll pen works ok on paper with a very thin line. Great for doing fine work and outlining. Good flow and lots of pigment. Doesn't work on canvas.
I used to LOVE Elmer's Painter's pens. I would buy the box of various colors when I had a 50% off coupon. They lasted for a long time and the paint spread consistently. The white worked like a dream. The quality has gone down considerably in the last two years. I'm so disappointed. They don't last, and they spread blobs too. You start a line and it's ok, but fizzles out after a couple of inches. I have not seen an improvement in the quality, so I'm going to quit buying the brand. I didn't have a white pen to use in the picture because I threw it out in a fit of frustration...lol.
The Faber-Castell pen is good. The only set backs: the nib is thick and you have to apply the lines a couple of times to get a solid white line. But it spreads evenly without blobs.
DecoColor also spreads a good line, but you have to apply a couple of times to get the solid line. It also smells vile of chemicals... I aim my fan toward the table when I'm using it.
The winner is: Uni-ball Signo. It draws a really good line, but is not permanent. Unfortunately. For paper work it's great, but not on canvas if you're going to apply something else on top. It smears. I did get a whole box of them for $23.00 at Jetpen's and if you buy, make sure to get the Japanese version. See the lettering on the box? Free shipping if you spend $25. I had some of their other colors as well, and they are great for writing, so smooth and easy.
What is your experience with white pens?? I would love to know since I'm still hunting for that perfect PERMANENT marker. If you want to keep in touch, please sign up for my newsletter at the top right hand side. :)