I have yet to play in any NT or even A tier events so my response will be in regards to the tournaments in the great state of Disconsin. It's a 3 way tie so my favorite would have to be which ever one is next on the schedule.
Manitowalk in the Park - Manitowoc, WI (2nd or 3rd wkend in July) TD is experienced so it's on time and organized. Lots of sponsors which means great players packs and lunch & supper provided.
Standing Rocks Open - Stevens Point, WI (end of April) TD could make this an A tier but prefers to keep it under the radar of the traveling disc golf gypsies as a B tier. Large field - pulls players from MN & IL.
Mad City Open - Madison, WI (late July or early Aug.) Was an A tier years ago but is a B tier now. Large field - draws top players from MN, IL, and IA. Courses are long and challenging. If you haven't heard Madison has a reputation as a party town.
All 3 of these tournaments fill up early so you must prereg. They pull in some of the best disc golfers in the midwest. Barry Schultz is a regular at all 3 of these as long as his national schedule doesn't interfear.
Down East Players Cup in Greenville, NC. Fun course, generous players pack and payout, but that's just a small reason to play. TD Scotty Faison and GVDG put on a tournament that makes every player feel like a member of the family. Every decision made from the size of the groups to where you finish is made to give everyone a fair chance at prizes, giveaways, attention, etc. The special treatment just never stops and everyone leaves feeling like a winner.
Charleston Classic the first weekend of December. We get to play Hampton Park (temp course) in downtown Charleston thanks to the guys from Innova coming down and setting up the baskets and tournament. It is also neat to see world class pros such as Brian Schweberger, Michael Johanson, Brian Mcree, Alan Beaver play in person.
Standing Rocks Open- Stevens Point, Wisconsin. Great Time, Good People, Beer. This is usually the first event of the year for me and I look forward to traveling to Plover to play a awesome event run by Randy. Standing Rocks Park is a picturous place that is special in many ways. I love bombing discs down the skill hill in attempt to win one of three baskets even though I lose several each year in the drink.