I would love to see Jamie Raskin step up. However, he's from Montgomery County - Van Hollen's old CD, if I recall. The folks in Baltimore and it's suburbs might not appreciate having two DC-area Senators. But, Raskin's got a lot of good press for being on the J6 Committee and one of the Impeachment Managers. He's a constitutional law professor - so I'd pay good money to see him go up against Cruz, Hawley, etc. If he does run, expect the Repukes to fling all sorts of mud his way as revenge.
Other possible candidates:
Dutch Ruppersberger (MD-2), former Baltimore County executive
Heather Mizeur from the Eastern Shore. She ran a good campaign against Andy Harris for MD-1, even though she lost She's got a lot of fans over on the Western Shore, too. Bonus points for being LGBTQ.
Brian Frosh - outgoing MD Attorney General. Made a lot of headlines taking on various corporations.
Kweisi Mfune (MD-5) He's in Elijiah Cummings old district, which also includes Columbia, MD.
Honestly, I don't think that Moore, Lierman, Brown, Miller, or Ivey will want to run for Senate in 2024. They're just starting their terms in January 2023. I think it would be disruptive to the state to have a current state-wide office holder running for Senator. If any of them would, it would be Anthony Brown.
My personal preference would be for Angela Alsobrooks, but it's the DC vs Baltimore thing again.
This all depends on whether Larry Hogan decides to run for President or Senator. He's made no secret about his loathing of TFG. He's probably going to go for the "sane Republican" vote. Unfortunately, there's not too many sane Republicans left. Even his hand-picked successor lost in the primary to a MAGAt from Fredneck. He's got a lot of good will here in Maryland and a lot of Dems would cross over to vote for him for Senator.