What's your favorite portage (if there is such a thing for you) and why? 

Yum Yum portage has to be one of my favorites.  Its got a little bit of everything.  Mud, rocks, challenging ledges to surmount, but best of all has to be the clifftop view about 2/3 of the way from Kash to Yum Yum.  Simply spectacular!  It's a great place to stop for lunch and just drink in the scenery.

As far as just a pleasant walk in the woods, the 2nd portage from Basswood to Kett is about as good as it gets.

The northern Cache Lake portage is also a very scenic walk and quite enjoyable if you don't mind the length.

Portaging is what you make of it, IMHO.  If you go into them with the mindset that they are going to suck, you're probably right.  If you go into them with a positive attitude and an eye for the beauty of the land, sometimes you'll find yourself a little disappointed to see the lake at the other end.