You're talking a fairly wide range of results. Finishing 9th then getting the 15th OA pick is still missing the playoffs. But putting that aside and assuming we're only talking about finishing near the bottom and getting a top-5 pick vs being a wild card and losing in the first round, you still have to look beyond just the result. Why we make or miss the playoffs is much more important than whether.
I can't agree with the "sucking now will make us better later" idea. The team is going to have a bunch of players at or near their prime. Players who we would expect to be contributors, to a greater or lesser degree, to any competitive iteration of the team in the future. If we "suck", it would likely be because several players who we need to be good, weren't. And that's probably worse for our long-term outlook than whoever we'd draft at #4 would be good for it. Conversely, if we make the playoffs it would likely be because those players perform even better than what we expect. Also better long-term than our 1st pick would be.
I want our younger players to do well, not just in terms of scoring points (particularly if 1/3rd of those points are the result of just a handful of big games), but also in learning how to impact games. Learning how to win. Obviously that would mean actually doing some winning. So if it's a choice between being mediocre, missing the playoffs, and picking 12th, or being a bit better mediocre, making the playoffs, and picking 18th I'd take the latter every time.