These are the two great rnb legends who have been singing for decades, though one, the younger, is more relevant up to present.
Note, as two active RNB ACTS, their archeivements are more honourable.
USHER: ACTIVE 1987_PRESENT,
8 GRAMNY AWARDS, THE THIRD ARTIST EVER TO WIN THE GRAMMY CONSECUTIVELY.
KNOWN AS A SUPERMAN PERFORMER ONLY AFTER MICHAEL JACKSON,
RULED MORE OF THE 2000S DECADE, PLUS EARLY 2010S,
POSSESSES ABOVE 3.5 OCTAVES,
SOLD OVER 65 MILLION ALBUMS WORLDWIDE,
HAS 9 NUMBER 1 RECORDS ON BILLBOARD HOT 100, THE FIRST ARTIST IN HISTORY TO TOP BILLBOARD MAINSTREAM AIRPLAY WITH FOUR SINGLES FROM ONE ALBUM,
HIS 2004 ALBUM, CONFESSIONS, THE HIGHEST FIRST WEEK EVER FOR AN RNB ARTIST, THE FASTEST SELLING RNB ALBUM OF ALL TIME, CERTIFIED DIAMOND BY THE RIAA, SOLD ALMOST 30 MILLION COPIES WORLDWIDE(REBASED).
BECAME THE 2ND ARTIST AFTER BEE GEES TO HAVE HIS TWO SONGS AS THE TWO MOST PLAYED SONGS IN THE WORLD IN A YEAR, YEAH IS LISTED AS NUMBER 2 SONG OF THE 2000S BY BILLBOARD.
USHER IS THE THE FIRST 2010S ARTIST TO COLLECT NINE CONSECUTIVE NUMBER 1 SONGS FROM THREE CONSECUTIVE DECADES, BEEN IN THE 90S, 2000S AND 2010S.
CONFESSIONS RANKED TOP SOLO ALBUM OF THE DECADE,
HE EMERGED THE NUMBER 1 HOT HUNDRED ARTIST OF THE 2000S,
he was listed at number 23 on Billboard greatest artists of all time. He is the only artist of his time to place that high.
Sold over 23.9 albums in the United States, becoming one of the best selling acts in the country ever.
Confessions is one of the best selling albums in history,
Usher's ever green club summer smash, Yeah, pioneered the genre Crunk&B,
Confessions is the last album to be certified 10x platinum ever in the United States, previously a worldwide record until British singer, Adele emerged with 21 circa 2011.
His 1997 song, You Make Me Wanna, still remains the second most endured record on the rnb chart with over 76 weeks, 2012 Climax is likely the fourth of all time.

R. KELLY: ACTIVE 1989 TO PRESENT,
3 GRAMMY AWARD,
4 NUMBER ONE SONGS ON BILLBOARD HOT HUNDRED,
RULED MORE OF THE 90S, PLUS HALF OF THE 2000S,
According to the RIAA, Kelly has sold 33.5 million albums in the
United Sates, making him one of the top selling artists of all-time.
According to Soundscan, Kelly has sold 16.0 million albums in the
2000's, making him the 5th Top R&B act of the 90's. Kelly is the
only male R&B artist to have amassed five #1 albums since 2000.
Kelly has sold over 50 million albums worldwide.
In March 2011, Kelly was named the most successful R&B artist of
the last 25 years.
In the 90's, Kelly had the most top 40 hits of any male artist with 15
hits.
Kelly is the most successful male R&B artist of the 90's.
In 2008, Kelly ranked at #62 on the Billboard Hot 100 All-Time Top
Artists list.
"I Believe I Can Fly" is #244 on The 365 Top Songs of The 20th
Century list as announced by the Recording Industry Association of
America (RIAA) and the National Endowment for the Arts (NEA).
"I Believe I Can Fly" is #406 on Rolling Stone magazine's 500
Greatest Songs of All-Time list.
"Ignition (Remix) is #494 on the updated version of Rolling Stone
magazine's 500 Greatest Songs of All Time list.
The R. album is listed as one of the 200 definitive albums of all time
by the Rock and Roll Hall of Fame.
"Ignition (Remix)" is listed at #19 on Pitchfork Media's top 500 songs
of the 2000s.
R. Kelly has the second highest debut of all time on the Hot 100, as
"You Remind Me of Something" entered at No. 4. Only Michael
Jackson's "You Are Not Alone", which was written and produced by
Kelly, debuted higher.
On February 8, 2002, Kelly performed at the 2002 Winter Games
opening ceremony in Salt Lake City. 72 million viewers tuned in --
making it the highest-rated opening ceremony ever.
On June 11, 2010, Kelly performed at the 2010 FIFA World Cup
opening ceremony in Johannesburg.
"Trapped in the Closet" ranks at #41 on VH1's Greatest Songs of
2000's
12 Play (6x platinum), R. (8x platinum) and R. Kelly (5x platinum)
albums are listed on RIAA's Top 100 best selling albums of all time.
Kelly has 13 gold albums, 12 platinum albums and 7 multi-platinum
albums.
Kelly has 11 gold singles and 7 platinum singles.
2000s (through 2007) Top Multi-Platinum Album Recipient with 5
multi-platinum albums.
2000s (through 2007) Top Platinum Album Recipient with 6 platinum
albums.
2000s Top Gold Album Recipient (through 2007) with 6 gold albums.