Not a believer in Randle. He has a lot of work to change his game in order to be successful in the NBA. Right now, he is a bench level player and he has got a long way to go in order to be a starter someday (jump shot, team defense, improving one-on-one D fundamentals). There is potential there but he has loads of work to do to get there. Cost is too high for a player that fundamentally flawed in terms of their style of play (no D, no J, so-so post scorer).
I like the Saric suggestion. That would be decent value for AB. Talented offensive player.
I am still a fan of and a believer in Aaron Gordon. I think he is a top 15 PF in the league right now and can be a top 10 PF down the road. I love his athleticism, defense and rebounding. A team first guy. Good handle and passing for a PF as well. I think he will show more of that in the future as he gets comfortable at PF. Great quickness on both ends. He is another guy I would open to trading AB for.
In terms of centers ....
I love Nurkic. Portland will probably keep him off the table now though. Ditto for Noel and Dallas. WCS is someone I would keep my eye on. Bradley is a high price but if WCS shows enough improvement in the close of the season I may consider it then.
Steven Adams would be a good one. Bradley and Westbrook would be terrific together. They have Oladipo though. Adams for AB would be a fair trade. Unlikely to get fair value especially when trading a small for a big. But that would be a good one if some thing changed in the future that would make OKC consider it.
So I guess WCS is the only option at center currently that makes sense for AB .
Two other ideas ...
(1) A big piece in a larger trade. Say for Jimmy Butler. Bradley + Nets pick + lesser future assets. Or say for a more proven big man like Andre Drummond. Nets 18 pick + Bradley. Something along those lines.
(2) A draft pick = trade Bradley for a future pick. Try to get another potential lottery pick in a few years time. Help reload as Horford / IT age. As Smart, J.Brown and Nets 17 pick become young veterans. Bring a new talented rookie into the fold.