If Boston doesn't win the title, I'd trade him this summer.
Brown for Towns straight up works. Short of that, I don't see how you get value for Brown.
For the record, I think Brown is a great player. I am not sure how the advanced stats don't support this. I don't ignore advanced stats or stats in general but I go a lot by what I see on the court. What I see in Brown is a smart, hard working, athletic player. That said, there may be a trade that works, I don't know.
Adding another player, I would trade Brown for Bam Adebayo also. Not sure if MIA would make that trade, or if MIN would trade Towns, but those are the level of players (and position) that I would consider trading Brown for.
Those are both reasonable trades. There are others, for example a trade with Toronto for Siakam + other pieces may make sense, like Siakam, Anunoby for Brown, Gallinari, Pritchard, Kornet (something like that). I think that would make sense for both teams, at least in theory. I'd call up the Cavs and see if Mobley was available. I think Brown would slot very nicely into Cleveland with Mitchell, Garland, and Allen, and Mobley would be awesome here as a big man. There would have to be other salary coming to Boston like Osman + Okoro. That would be an interesting trade. I don't think Cleveland would do it, but it would at least make sense for both teams. I'd consider something like Ayton + Payne for Brown. Probably wouldn't do that, but I'd at least think about it. I'd also consider Anthony Davis or Damien Lillard who both may become available this summer (and if Wash was giving away more than Beal I'd consider him as well). If New Orleans wanted to trade Ingram or Zion, again I think that could make sense.
I'm sure there are other 1 for 1 type trades that make sense, but there are also 1 for 2 + draft pick trades that I think could work. Atlanta for example, like Brown, Gallinari for Collins, Bogdanovic, 2 1st's (though I'm not sure the Hawks have any to trade because of Murray). Obviously Collins and Boggy aren't collectively as good as Brown, but the extra 1st's are helpful and those 2 guys would at least fit stylistically with the C's. The Nets could offer Bridges, Harris, and a couple of the Phoenix/Dallas 1st's for Brown. Again Bridges is not as good as Brown, but a solid fit with Tatum and extra draft picks to utilize. Perhaps the Thunder want to compete next year, I'd think about Holmgren + Dort (and a couple of the billion picks they have) for Brown if Holmgren's medicals checked out.
Lots of options potentially out there. Of course none of those players may be available either.