My favorite character meal in either DL (have done them all) and WDW (have done all but one) is Goofy's. We've gone 10+ times and never had anything but a wonderful meal. I am partial to an early dinner at Goofy's but love their breakfast too. The selection of food is great and being able to monorail down to the DLH is very convenient. We've always had a great number of characters visit our table. Always at least one princess, Goofy, Chip and or DAle, Minnie, Pluto (he's out front) and then at least two other characters that have included: Peter Pan, Wendy, Alice, Mad Hatter, Genie, Baloo, Aladdin, Captain Hook and once we had Fairy Godmother (long ago on that one before she was at other meals). So for us, we've never felt jipped on characters and they've always come around. Whenever I go to DL with family members, this is the one I take them to since we've always had the best food and a good amount of characters.
I also love Lilo and Stitch. Its never very crowded, the food is great (love the pineapple scones) and the games they play are very fun. So that's the breakfast we usually do now, since we always do Goofy's for dinner.
I like Minnie's for the convenience of being in the park and the fact I love the Plaza Inn. But to me to the food is so lackluster. I don't like the long lines (in my opinion this restaurant is not set up to handle a crowded buffet) and the selection is not nearly as good as the two I mentioned above. But the convenience factor is huge and the amount of characters they have is awesome. But for what I pay, I do have to say it want better food. I have been doing Minnnies for years, back when it was Pooh and friends, and then for its brief stint as a princess breakfast and I have always found it hectic and very disorganized. Of the 15 or so different character meals I have done over the years at DL and WDW, it is my least favorite. But again, still fun (so Minnie lovers, don't hate or flame me lol). But last time we spent over two hours there while my nieces and daughter waited patiently for several characters to come around (and this has happened there before, I swear we are jinxed with this place) and we finally gave up. But the manager did give the kids pins which was nice.
I'll also add Storytellers is wonderful food. The characters are also fine, if you like those particular ones. If you have little girls that want princesses or the more main stream Disney characters, don't pick this one. But for older kids and people who want amazing food, Storytellers is awesome.
I haven't ever done breakfast at Ariel's but I've enjoyed many lunches and dinners there so I am betting its a lot of fun too!
And to the poster who asked, the characters do come outside. But in my experience, it takes them awhile. They seem to move in a more orderly fashion inside than outside.