Right now I'd say the biggest needs are as follows--
1). OT
2). DT
3). CB
4). WR
5). Front 7 depth
Bonus: backup QB (for once)
The nice thing this year is while the Browns do have a lot of money to spend, they don't need to spend it all.. They're really well positioned with the roster with really one or two bigger signings, they can really focus on depth and keeping their own players... It's a good place to be in..
Here's some players I would look to, to fill those needs:
QB/
Josh McCown -- if he wants to come back, I'd be all about him filling the backup QB role.. Yes the room already has Stanton but McCown has been just as valuable and shown he can still play if needed for just a game or two... The backup QB market is very thin, so safe to say this is choosing from the bottom of the barrel...
Also: Geno Smith
WR/
Tyrell Williams -- he would be my top target on the outside... The Browns have the underneath covered but they need to continue to add size and deep speed... I don't think adding a true #1 is necessary as Landry, Higgins and Callaway all need playing time... So adding a part time player who provides the traits needed in this corps seems to be best suited...
Also: Jermaine Kearse
LT/
Ty Nsekhe -- this might be a 2-3 year stopgap but he's someone who could fill that role real well until they're able to invest further capital at the position...He's been a part time player for the last 4-5 years in Washington but has consistently been one of the better backup tackles and filled in at LT with little drop off...
DT/
Sheldon Richardson or Mohammad Wilkerson -- this would be a fun 2-3 year investment until they have to start paying the rest of their D-Line... While neither a clean fit, their disruptive nature would be a welcomed addition..
Also: Grady Jarrett
CB/
Bradley Roby -- you could make an argument that similar to WR, the Browns make up for elite CB play with a deep CB room... Ward is the #1 but Mitchell, Carrie and Boddy-Calhoun all play roles... Adding another young guy with upside and experience would be a wise move...
Also: Ronald Darby