I have used Extensis Portfolio from ages ago, and now are a "enterprise" priced POS(software).
I also have used MediaPro, but there was issue with TIF files and some glitches when I purchased from PhaseOne for about $50, and now they wanted almost $200(with no update price) to find out if those glitches are still there or not. No thanks.
I have PhotoSupreme, its good, but...I have Imatch, its good, but...Photo Mechanic on the MAC is good...But I actually still use ACDSee Pro.
This makes a lot of things easy to do. Its fast, the DB is not required. It doesn't crap in all your folders with unknown files. Interface is configurable.
There are others like... FastRawViewer, BreezeBrowser, FastStone, IrfanView, Zoner, Camstasia, AZImage, .....They each have something I was OK with but preferred ACDSee over. Picasa perhaps is another, and ImageSorter.