Because we were able to visit four different character dinings for breakfast, I think I have a pretty unique perspective on the different options.
PCH GRILL: Hands down, our (mostly mine) favorite. Incidentally it was also the least crowded. We arrived at 7:20 in the morning. It was an early breakfast by anyone's standard, especially with a four year old and a two year old. But, it was well worth it. We were among the first people to be seated and we were rewarded with the full attention of Stitch. Our kids had a blast and Stitch seemed particularly taken with our oldest and kept trying to steal her food.
The kids also got to go up front and learn how to do a Hawaiian dance. Our youngest fell in love with Mickey, much to my surprise. She snuck away from the table and sought him out. Luckily there was no one waiting in line to see him so Mickey took a few extra minutes to show her how to hula. Thanks Mickey!
Goofy's Kitchen: My husband particularly enjoyed this breakfast. I know it was because they had the best buffet- no question. But, I was a little underwhelmed by the character interactions here. We were seated in the back, showed up a little later and didn't feel like we got the chance to see as many characters.
I do think that I will make an earlier reservation next time and I'll learn to just relax and enjoy the food a little more because the Buffet here really is top notch.
Chip and Dale's Storyteller's Cafe: This breakfast setting was gorgeous. Located in the Grand Californian, the restaurant was stunning. I almost felt out of place in my jeans! The servers were OK but the characters were a hoot. Two of the characters (Meeko from Pocahontas and Terk from Tarzan) stopped by our table for an extended visit. My youngest got a kick out of trying to share her drink. The characters really made our girls feel extra special. And the special camp guide marched the kids around the restaurant in a fun little bear hunt.
One little tip: Try an earlier breakfast here on a day you plan to visit California Adventure. You can hit the special entrance for resort guests inside the hotel, saving you a bit of a walk.
Minnie and Friends at the Plaza Inn: This was probably my least favorite in regards to quality. I'm not sure if it's because we were stuck sitting in the sun or because I thought the staff working the omelet station that day were rather cranky. It also could be that it was our last day of the trip and we were all a little tired and stressed... The characters were pretty good. My oldest took a dive off of her chair and Minnie hurried over to help her up, something she still talks about! You'll see some fun characters you might not catch elsewhere, like Captain Hook.
Ariel's Grotto: We didn't do the character dining here, but we did have dinner here. The setting is stunning. We were lucky to sit outside on the deck overlooking the Pier. It was lovely. The food.... not a huge fan. I'm a hometown girl. I love going to fancy restaurants but I like food that I'm familiar with. The food here was a little too... uppity for my taste. I would recommend hitting Ariel's for a different meal. The dinner didn't feel very kid friendly to me. The staff was very nice though and the restaurant was really nice.
If you like more upscale food choices, you'll like the food here.
You should do at least one character dining on your trip (though four may be a little too much-- it's a lot of big breakfasts) simply because you get to see so many characters. We didn't have to stalk the characters out around the park (though we did scope out a few) because we'd met so many at breakfast. This saved us a lot of time in the park. Plus, if you hit breakfast early enough you'll get a lot more quality time with the characters than you will waiting in line.