I agree with Evilo, Juve have to be considered comfortable favourites. Their backups alone could probably challenge for a CL spot in Serie A, it's just the reality of the situation.
Inter have been declared the winners of the summer mercato for 3 straight seasons , and only last year actually made top 4 , and it took an epic collapse by Lazio on the last day of the season for it to happen. I won't lie, I've liked quite a few of their signings (especially Lautaro M), but I don't think it's a forgone conclusion they're the 2nd best team in the league. This will be the first year they've had to deal with CL under the new regime, let's see how their domestic campaign can handle it. Spalletti is also a loose cannon.
I honestly think Napoli may struggle to even get top 4. That roster isn't as good as people think it is. Sarri was just that brilliant. We'll see how it goes , but I'm pretty apprehensive about their chances at top 4 , let alone their titles hopes.
Roma should be top 4 and potentially more if our kids improve and contribute. Our starters are all veterans that are capable of achieving top 4 - they are the basement- the kids are the ceiling. We go as they go if we actually want to mount a serious title challenge. Roma's veteran players aren't good enough to beat Juventus over the course of 38 games , that's just the truth. The highly rated youth Monchi has brought in have to move the needle. Cristante, Lo. Pellegrini, Karsdorp, Lu.Pellegrini, Coric, Schick, Kluivert and Under dictate just how high the ceiling can be. Also , I wouldn't be surprised if we bring in a couple more signings before the end of the window. N'Zonzi and Dennis Man being rumoured to be very, very close at this point.
Lazio has held onto SMS and made a few prudent moves , I wouldn't count them out. It's an odd collection of talent, but Inzaghi has them playing a great brand of offensive football, and they squeeze every penny out of their signings. Immobile and Lucas Leiva , for example. As much as I dislike them , it's a well run club, and that can go a long way in football sometimes (Serie A in particular).
That leaves Milan , who have a ton of things they need to fix, but have a good young nucleus to work with. I think they likely need a year to clean up the deadwood , and fix the issues left by previous ownership. But I must say I've been impressed so far , so maybe they'll surprise me this year. And I I wouldn't be surprised to see Antonio Conte brought in sometime this season.
Fiorentina/Atalanta are probably the other two contenders for top 6 , and both boast great collections of young talent, but no genuine threat for a Champions League spot, imo.