1997 was amazing, but Russo wasn't "head writer" until the end of the year. Midcard was horrendous, but the Main Event carried it.
1998 was a great year. Main Event carried again, but the midcard stepped up, more gimmicks were introduced, but they weren't crazy.
1999 was objectively terrible but the company was so popular people didn't care. Rock was midcard for like half the year for some reason, despite getting the loudest reactions after Austin. HHH's initial push is some of the worst television that I could remember seeing. Even at this time, I was flipping back to WCW more, and they fukking had Rodman and Savage cursing at each other. Midcard just threw whatever wacky gimmick they can.
2000 was an amazing year and overall the best balance between wrestling and an engaging product.
I have love for 1997 though, I think 1997 has a slight edge because it was just 100% fukkery and could never be mimicked. You had Bret and Shawn's shyt leaking on to the show, Austin come up, Taker/Kane stuff, Mankind promos, HHH coming up, Rock, in the late half of 97 was coming to his own, product was still a bit grounded in reality. Like 1997 shows feel nothing like a 1999 product, because it was still being shot like it was 1993-1996, despite being different from those years.
But rant's aside, to answer the initial question. I think it was better without him. 1998 is his full year, and while a fun year all around, he peaked with Survivor Series 1998. That was pretty much his magnum opus and after that you could see everything fall apart. WM 15 has to be one of the most forgettable shows of all time, because Russo didn't give a shyt about anything but TV. Even in 1998, you could tell other people were helping him with promote PPVs and shyt because most of those PPVs were stronger than anything that came in 1999.