It's so nice seeing Kero and Iggy weigh in on this issue: having my fellow Toad fanboys around certainly helps out. =)
As far as my luck goes, Toad will not be in Brawl because I want him to be. But should the planets align and my wish be granted, I will be one happy Smasher. Toad has been my favorite Mario character since the days of SMB2. I would cruise through each and every level as my little mushroom hero, taking advantage of his intense strength and speed. Needless to say, it was disappointing to see him relegated to host status in the first few Mario Parties, but his dominance in Mario Kart (especially 64) was a welcome addition to Toad's résumé. Animal Crossing introduced me to Wario's Woods, which I found quite enjoyable--partially because of Toad, of course. Seeing him in MP5-8 and MK:DD made my heart fill with joy, but his exclusion from Melee really hurt. I thought it would finally be Toad's time to shine; I can only hope that Sakurai gives him his chance this time around. I think that, while Sakurai acknowledges that both have sizable fanbases, Toad would have an edge because of his seniority in the series and his eternal presence in the Mushroom Kingdom.
Surprisingly, it's not Bowser Jr. that I hate. It's Petey Piranha. Bowser Jr. is interesting in that he is evil, just like Daddy, but he's more agile and at least he speaks. Petey, on the other hand, stands there, flaps his leaves, squeals like a mandrake, and vomits sludge. Wow. There's a real winner if ever I saw one. =/
In short, Toad for Brawl. Enough said. =)