I wouldn't dwell on getting the 1st pick too much, because the odds are very low.
That said, I would absolutely prefer to keep it rather than trade it. Ben Simmons is a beast. A college freshman, he's dominating college in a way that suggests he's already far too good to be playing against other college players.
Typically, that's the sign of a future superstar.
Any other pick in the draft, I think I'd be OK to see Ainge trade it, along with other assets, for an established player. But if it's Simmons, positionally versatile, great passer, awesome in transition -- I want that guy learning to play the game under Brad Stevens. He could be our Tim Duncan. For real.
Sorry if I wasn't clear. The main question is do you take a step back and trade some key players to continue a draft rebuild and a plan to build around Simmons or just add Simmons to the mix and try to compete. I think they should step back myself, deal IT and AB for another top pick.
As I see it, the core of the team right now is Isaiah, Bradley, Crowder, Smart, Sullinger, and Olynyk. Not to say that those guys are irreplaceable by any means, just that those are the most important players on the team. All of those guys are pretty young.
I think if we were to get Simmons, I'd want to hold onto those guys as the main part of the rotation, though I wouldn't be too concerned with re-signing Sully if somebody makes a big offer for him.
I would, however, be happy to let Amir, Jerebko, Lee, and Turner go. I'd leave room for the youngest guys on the team -- Rozier, Hunter, Young, Mickey -- to prove themselves, not to mention whatever other rookies we have on the roster next season. We have a ton of draft picks, after all.
If we are fortunate enough to get Simmons, it will mean that there is a path to contention, provided he realizes his considerable potential. There wouldn't be any rush. At the same time, no need to take a step back by trading away any of our main role players, who are all quite young and cost-controlled.
In short, I'd be happy to head into next season with a starting lineup of IT, Bradley, Crowder, Simmons, and Sullinger / Olynyk, with a bench mostly comprised of rookie contract guys.
That team might not win as many games as this year's team, but that team would have a bright future. If Simmons were to have a really good rookie season, I wouldn't be surprised if top FAs were really interested in joining that young Celts team.