Dan:
I've been lucky enough to take about a dozen Canadian trips, maybe more and I'm not sure you gave enough information to give you a good specific answer. What type of fish do you want to catch and how much do you want to spend? Do you want to be fully guided or do some fishing on your own. Cook your own meals or American Plan? Dropped in the wildnerness and be the only people on the lake or fish from a main lodge? Nueltin Lake is considered the premier Canadian fly in lodge with many options on remote camps and lodges but pricey and no walleye.
We did a combined fishing/duck hunting trip to The Pas Manitoba this past fall that was great and economical. Wish we had time for more fishing but the management was outstanding and willing to go the extra mile to make sure you have a good time. They had great food and many options to fish including walleye, lake trout, northerns and brook trout. All our fishing was unguided but guides were available. It wasn't fishing, it was catching (it was also October). My best advice wherever you go is to get several references on the staff and call every one of them. The outfitters will tell you that Gunisao Lake is the best walleye lake in Manitoba but I haven't been there. Gods, Reindeer, are well known. In Ontario you have Kesagami, Lac Seul in the upper echelon.