When it comes to ink pads we have way too many options to choose from. So many different colors, so many different features. It's not easy to choose the "right" ink pad for your project, especially because you normally can't use the ink pad before you buy it (this would have helped to prevent me from buying ink pads that I didn't like).
I can't tell you which ink pads are the best and I am not an expert in this area (Jennifer McGuire is one) but I can share my experience I had in the past few years with different ink pads.
I didn't edit the photos to keep them as close as possible to the reality and you can click on most photos to enlarge them to see the stamped image up and close.
BLACK INK PADS
My first ink pad I bought was the StazOn ink pad in black. It's for every surface, you get a really crisp image and it dries very fast. I use it for paper, photo paper and vellum. I bought different black ink pads in the past as well but I always come back to StazOn. Black is also the most used ink in my projects.
You get the best image with the StazOn ink pad. The VersaFine and ColorTheory ones are good as well but the image is less crisp.
What I don't like about the black color theory ink pad is, that you almost can't remove the color from the stamp afterwards. This only happens with the black one. It doesn't change your stamp but it's black after you used this ink pad.
COLORFUL INK PADS
I recently started to use more and more colored ink pads instead of only the black one. Most of the time I used the Color Theory ink pads but a few weeks ago I discovered the VersaColor and MementoLuxe inks which are really really awesome. The different brands are also different kind of inks. The StazOn ink pads are solvent based, Color Theory ink pads are dye ink, VersaColor and MementoLuxe ink pads are pigment inks. There is a really great video about the difference between dye ink and pigment ink on Jennifer McGuire's blog.
The MementoLux ink pads are new to me. I bought them a few weeks ago from AliEdwards.com and I'm super excited to use them because they give you a really really crisp and rich image and they don't have a problem with thin lines. So far I only own these three colors but I think I'll go and buy some more of them soon.
I have (almost) every color from the Color Theory ink pads. They are from StudioCalico and were part of many different products with the same color. (It seems that there are only the ink pads available anymore). These aren't very expensive and don't need much space because you can easily stack them. The image is not as crisp as other stamps but I like that you get some beautiful second and third images. (I used that for this card).
Another new favorite are the VersaColor ink pads. I started to use them a few weeks ago and love love them. So far I only own these two colors (and a white one). The image you get is extremely crisp and the colors are beautiful. I am a huge (new) fan of them.
The colored StazOn ink pads are okay but interestingly the image is not as crisp and clean as with the black one. The inks dry very fast as well and work very good on different mediums (like wood for example).
The StampinUp ink pads are another favorite of mine. There are many different colors to choose from and they coordinate very well with the different products with the same color they offer. Again, the image is not the best one but like the Color Theory inks I especially like the second and third stamped image. You can clean the stamp really easy after using them.
When stamping onto photos with colored ink pads I mostly used the ColorTheory ink pads. Now, I will use the MementoLuxe and VersaColor because they are a tad bit better. I print my photos at home with my HP Photosmart C5280 on Canon semi gloss photo paper and noticed that sometimes the ColorTheory ink removes part of the photo. I guess this only happens when you print your photos at home.
OTHER INK PADS
From the ColorBox ink pads I only own the gold and silver ones. They are also pigment inks. The gold is not the best (as seen in the photo) but I really like the silver one. So far I haven't tried other brands for gold and silver ink pads, but I will try the VersaColor ones next.
The Hero Arts Neon Ink Pad in Orange is really cool. You can't really see it in the photo but the neon is actually neon. I like that ink pad for example for a stamp I add on the back of an envelope or for a fun card. Compared to the StazOn is the image less crisp again.
The Hero Arts Shadow Ink in Wet Cement gives you a beautiful muted look. Perfect for backgrounds but I also like to use it when the image shouldn't pop out that much.
The ColorBox Fluid Chalk Ink Pad is another great one. As the name says it, you get a chalk-like look. The red is a beautiful one. But to clean the stamp after using it with this ink is not that simple because you have lots of ink on your stamp.
VersaMark ink pads are mostly used for embossing because they don't dry very fast. But I also like to use it as it is because it gives you a special look when stamping on a darker piece of paper. (and with darker I mean anything besides white)
WHITE INK PADS
I have four white ink pads in my collection but I can only recommend two of them; the VersaColor and the Memento Luxe. They give you a clean image on paper and work very well on photo paper as well. The VersaColor is not as white as the MementoLuxe on paper, but you get the better image with the VersaColor ink pad. All four of them are pigment inks which also means that they don't dry that fast.
The image of the white ink pads on photo paper is almost identically with the MementoLuxe and the VersaColor ink pad. The ink dries in a few minutes but you will smear it when you rub your finger with pressure over the image.
So, if I could only pick one ink pad I would choose the StazOn ink pad in black. It's my most used one, works well on everything and gives you the best image. When you want to add color, I'd suggest VersaColor ink pads for a crisp image on paper and MementoLuxe ink pads for photo paper, StampinUp and ColorTheory ink pads if you want to play with second and third time stamped images and when you want a really good white ink pad the VersaColor one would be my choice.
As I already said, I am not an expert in this area and only share my favorites based on my experience. If you want to learn more about all the different ink pads and how they work I highly recommend Jennifer McGuire's blog.