I think the food at DLP has improved in the last 3 or 4 years, both in terms of the range of stuff on offer and the quality. There should be sufficient variety to satisfy just about all tastes.
I'll add another vote for Anette's Diner in Disney Village. This serves good burgers, chicken, ice cream sundaes, etc, all in a fun atmosphere. If you want a proper full-service restaurant, but not 'up-scale' food/prices this is a good option. It is very popular, so eat early or late to avoid the queues. We often pop out of the parks for an early lunch at Anette's (although it's in Disney Village it's only a few minutes walk from both main gates).
For fast food with a UK slant I would vote for Toad Hall for traditional fish&chips, roast beef sandwiches, salads, etc. This is the only place at the resort which does proper fat chips rather than the skinny french fries served everywhere else!
For more unusual offerings I would say that Restaurant Agrabah in Adventureland is a good place to try, offering a range of arabic & mediterranian inspired food. This is an 'all you can eat' buffet. Great themeing, so worth a visit if only for this.
For pizza I would say Bella Notte or Colonel Hathi's Pizza Outpost (my favourite for pizza) are the best options. However, I would like to make a special mention for the PizzaBurger at Buzz Lightyear's establishment. Although the venue has its problems, the burger where the bun is made out of pizza bases is unusual and worth a try!
For full service, high quality food in
Disneyland I would say that the Blue Lagoon or Walt's are first class. The setting for the Blue Lagoon is amazing (it's actually part of the Pirates of the Caribbean ride!) and I enjoy the food there a great deal (although some express disappointment that portions are a bit small). Walt's is another great restaurant, with rooms overlooking Main Street. Honourable mention goes to the Silver Spur Steakhouse (if you like steaks) with it's open kitchen which allows you to look at the chefs and their flaming grills.
In the Seqoia Lodge I like both the Beaver Creek Tavern and Hunters' Grill. If you really want to push the boat out the California Grill in the Disneyland Hotel, with its award winning chef, is regarded by some as the best restaurant operated by Disney in any location around the world. I've eaten there once and enjoyed it, although it wasn't cheap.
Not eaten much in the Walt Disney Studios, so can't offer any advice for that park. In general I would say that if you don't like queueing you should plan on eating early or late (eg midday or after 2pm).
Regards
Rob