I like versamark for embossing...
I like StazOn for stamping over photos or on vellum or if you are going to colour in the stamps (it's permanent ink)
I like TH distress inks for just regular stamping (or sometimes for embossing)
You might want to google inks for a chart (or maybe there is one on here somewhere?) ETA: oops I think I replied at the same time as Stick
Different inks are made for different things....
I have mainly clear stamps and for the most part I use Jenni Bowlin inks which give me a really crisp image and also works well with Copic markers. I've also had success with Memento, Colorbox Chalk, and Staz-On inks.
You could also check out companies that manufacture clear stamps and offer a range of inks, such as PTI & CTMH. It makes sense that they would ensure their inks are formulated to give good results with clear stamps.
That said, not all clear stamps are created equal, so make sure you're using high quality photopolymer stamps for the best impression...
For stamping images, I use Stampin' Up colored inks. Depending on what black I need, I use stazon or SU black ink.
I love TH inks but I don't stamp with them. I have never been able to get crisp images with them no matter what kind of stamp I use. I love them for distressing though!