Simple. For anything that SSC and HT would be doing at the same time, I would watch to see who has the better product. So if they both did a Mark VII Avengers Iron Man, which looked the best between the two I'd buy. I have to say this as well, cost will determine a lot. If HT gives me a piece that I can mimic the pose of an SSC piece then it's a no brainer, especially if the prices are the same or if HT's figure comes in cheaper. SSC would obviously have to up their game in terms of QC but also in terms of pose and "extras" as HT's might include Stark portraits, interchangeable parts stock whereas SSC would have some of that as "exclusives".
More people in the 1:4 game the better, it forces everyone to up their game. What will be interesting is if for example the new Superman film, all three companies Enterbay, Hot Toys and Sideshow do something, then you've got serious competition which only benefits us.