Ooh, that's a tough one. I would press, because the Wario shoulder bash is very iconic but hasn't been around much since Wario World (apart from some micro games in Ware-correct me if I'm wrong, Wario experts), yet the Boost has been missing in Sonic's set despite being around since 2005's Sonic Rush and still going strong (as far as us fans are aware). And I'm obviously a bigger Sonic fan than I am a Wario fan. Plus it's just downright weird having two spindashes (I think one is supposed to reference 2D Sonic, and the other Sonic Adventure 1&2? Still makes no sense)
TL;DR Pressing the button because I consider Boost more important to Sonic than the shoulder bash is to Wario-you don't see Wario fans referring to Land games and World as "the Shoulder Bash era" for example.
Target Smash returns at the cost of Stage Maker.