I look at animated gifs all the time and have found far and away the two simplest ways to do it are:
1. Single-click the gif icon, then click the "Quick Look" icon in the Finder window's "toolbar" (if it isn't in the toolbar yet, then in the Finder "View" menu choose "Customize Toolbar" and drag the "Quick Look" eyeball to the toolbar).
...or...
2. Just drag the gif icon onto the Safari (or FireFox) dock icon.
Either way is equally easy - I choose one or the other, depending on my mood and where the cursor is on the screen.
You also try this:
Single click an animated gif icon, then choose "Get Info," and in the Get Info panel, choose "Safari" from the "Open With..." drop-down menu. Voila! Then ALL your animated gifs (and non-animated gifs too) will automatically open and play in Safari, just by double-clicking on them!
(I wish there was a way to choose "Quick Look" from the "Open With..." drop-down menu, but I guess it doesn't count as an "application," being rather a built-in Finder feature.)