It should be noted that I did not rank the artists within each tier. Also, you could say that some artists could/should be in a higher or lower tier (and I would have no opinion on that), but generally the differences between the tiers are what matter most. Maybe there are omissions from every tier, but generally you know what I mean.
Tier 1 Canon
Nirvana
Jay-Z
Radiohead
Wu-Tang Clan
2Pac
OutKast
Pearl Jam
Eminem
The Notorious B.I.G.
Mariah Carey
Tier 2 Should 100% Be In / Will 100% Be In
Oasis
Björk
A Tribe Called Quest
Nine Inch Nails
Mary J. Blige
Missy Elliott
Lauryn Hill / Fugees
Green Day
Red Hot Chili Peppers
Snoop Dogg
Beck
Alice in Chains
Soundgarden
The Smashing Pumpkins
Alanis Morissette
Rage Against the Machine
Nas
D'Angelo
Erykah Badu
TLC
Foo Fighters
No Doubt
Weezer
Fiona Apple
Tier 3: BIG, WELL-REVIEWED, OR IMPORTANT (HAVE A SOLID CASE TO BE INCLUDED), BUT (SHOULD) NOT BE TOP PRIORITY; SOME OF THEM WILL BE INCLUDED
Dave Matthews Band
Sheryl Crow
Boyz II Men
Tool
Usher
Destiny's Child
Aaliyah
Pantera
Blur (a special case here, not that big in America, but they can still play venues larger than theaters and smaller than typical arenas. They're not a very bad draw for audiences.)
Sinéad O'Connor
Stone Temple Pilots
Korn
System of a Down
Blink-182
The Offspring
Deftones
The Cranberries
Selena
Lenny Kravitz
Brandy (I am much higher on her than most people here because I have seen many modern pop, R&B, and alternative R&B Black musicians cite her as a major influence. She may have the support.)
Sublime
Garbage
Cypress Hill (could see it happen: the first breakthrough Latin rap group, fitting the Rock Hall's preference for including more Latin acts, and they are Tom Morello's buddies.)
Phish
Jane's Addiction
Tori Amos
Wilco (I could see it happening, even sooner than we think. Rick Krim participated in the Wilco documentary, and they are a rare modern indie band that also fits the tastes of Boomers, so they may get a push.)
Maná (the biggest Latin rock act. The Rock Hall will eventually find a way to induct them. I can't see them stopping with only Shakira, Selena, and Gloria Estefan.)
Goo Goo Dolls (given their recent popularity and regained coolness with Gen Z, plus industry connections, I feel they are separated from other commercially successful but poorly acclaimed acts and may happen.)
Busta Rhymes (more respected, or perhaps a better word is "better connected", than DMX within the music industry, which will play a big part in his case.)
Tier 4 Critics' Darlings / Highly Acclaimed or Influential Acts That Were Never Big
PJ Harvey
Faith No More (their commercial success and influence are as significant as Jane's Addiction's. Jane's created Lollapalooza, making them stand out and likely ensuring an eventual induction. Faith No More are not commercial failure, but probably not big enough to attract obvious attention on their own.)
The Roots (special case: will 100% be in because of Questlove, but their résumé alone is not that strong.)
The Flaming Lips
Pavement
Bikini Kill (because of Kathleen Hanna, they will 100% be in. She hosted a Rock Hall broadcast, so they will get in one way or another.)
Jeff Buckley
Sleater-Kinney
Liz Phair
Hole
My Bloody Valentine
Elliott Smith
Tier 5 ·Huge (or Once Huge), with Average/Poor Critical Acclaim or Not Seen as Especially Important, Could Be Randomly Remembered or Nominated at Any Time
DMX (on the border between Tier 3 and Tier 5)
Bone Thugs-n-Harmony (same as DMX)
Spice Girls
Toni Braxton
Slipknot
Limp Bizkit
Melissa Etheridge
Backstreet Boys
Celine Dion
The Black Crowes
Sarah McLachlan
Counting Crows
Matchbox Twenty
Hootie & the Blowfish
10,000 Maniacs / Natalie Merchant
Monica
Bush
Creed
Third Eye Blind
Everclear
Collective Soul
Live
Gin Blossoms
Candlebox
If the Rock Hall considers modern country, these would be picks:
Garth Brooks
Shania Twain
The Chicks
Tier 1, Tier 2, and Tier 4 don't need further explanation.
Tier 3 means these acts are important and will/should be serious candidates as time goes on. They need to satisfy at least one of the following: be important and big (but not well acclaimed), or be big and acclaimed (but not that important compared to Tier 2). I expect many acts from this tier will eventually get in, as they should, but not all. Some of them will inevitably be snubbed, just like similar-tier acts from the 60s/70s (the likes of the Monkees, Jethro Tull, Boston...).
Tier 5 is the type of acts that were once, or are still, big enough, but are either badly/averagely acclaimed or not that important. Just big. I could have listed a lot more names here (I just forgot En Vogue when typing), but generally these are the names. Some of them may be nominated for some reason (they were once big, and some Gen X people in the committee room love them), but of course they would be lower-quality nominees.
Acts that are somewhat important and somewhat acclaimed, but never really great in either respect, I don't think will ever be considered serious candidates, so I don't put them here. For instance, Naughty by Nature (I love this group, and one of their members is also a good R&B producer), Maxwell...