Sonic's best stage is Wuhu Island since it has both the large flat surface and the touring attributes, but even if we ignore that one, I think touring stages are good for Sonic on average. Sure FD is a really good Sonic stage as is Duck Hunt, but then again, BF is by far the worst Sonic stage and he's pretty awful at Smashville too with T&C being about as good as a typical transforming stage for him (I'd say T&C is about equal to Skyloft and Halberd for Sonic but worse than Castle Siege and Delfino). In general, while short walls aren't Sonic's favorite stage feature, he can pretty easily stall out transformations that don't go his way while really capitalizing on good ones. None of the transforming stages are too platform polluted (especially not with low platforms which Sonic *really* hates), and walk-offs are extremely pro-Sonic. If the ceiling ever gets low, Sonic has some really dirty juggle set-ups as well.
As per Mac, he's kinda funny. His first stage preference is absolutely hating certain "automatic loss" stages that have permanent geographies that just fundamentally defeat his basic gameplan. Out of the EVO stages you have Duck Hunt and Smashville, and more liberal stage lists add Kongo Jungle 64 and arguably Dreamland 64 (the latter needs more exploration for Mac, but early signs aren't good). Platforms that in any way assist stall are just toxic for Mac (like people don't even get it; Smashville is so ridiculously unfair for Mac), and in this way, transformers are good since none of the platforms are permanent. Obviously FD is by far Mac's best stage, and honestly he probably likes T&C more than any transformer, but the transformers are probably similar value propositions to Battlefield and Lylat for Mac. I wouldn't really list Mac as a pro-transforming stage character, but he doesn't get screwed by them which is the critical thing since for Mac it's all about not being screwed by the stage (note that replacing Halberd with Dreamland in a 9 stage list is extremely brutal to Mac's tier position since Mac can no longer ban every awful stage for him). This also presumes customs on since Mac really needs Grounding Blow to deal with general platform camp on at least Battlefield; after seeing it in action, I'm truly mind-blown that people think Mac has bad customs as opposed to him being one of the most custom reliant characters in the game. If customs are off, you can ignore this entire paragraph since Mac is just plain a non-viable character in that scenario and hence his stage preferences are irrelevant.