In stock form, you're going to get a bit more power, lateral stability and heaviness of ball out of the ATS 98. Overall precision might be more of a wash. In general, the ATS will be a bit more of a "meat mallet", the Phantoms a bit more open, airy and creative. For modern singles around or over 3.5-ish, the ATS is the better stick for most players IMHO. For doubles or casual / older-school singles, the Phantoms are more justifiable.
TL;DR - I see you keep posting somewhat random questions about certain frames lately (which is fine, by the way), but I sense you're looking for some overall guidance. Why don't you make a general help thread, describing yourself as a player, what you've been playing with (both racquet and strings), what you're struggling with or would like more of in your setup, and we can try and give you guidance based on that.