I believe the older games played before are not the same as this weeks' game will be. For example lazio was ahead of Roma last year, and very close the year before. But, this year Roma literally tried to become the leaders of the league in the recent weeks, the only draw would be to Inter who is second in the league so it is a bit looking like Roma is the favorites.
AS Roma in this season are facing same doubt from observers like Inter Milan had in the previous season or AC Milan in the early of this season. They are building their team after some bad seasons and people are still wondering how they can manage to maintain their good results. They are doing well and have not yet shown any signal of loss in form. No serious injuries in second half of season can help Roma to take a spot to Champions after 3 seasons out. Roma has a young blood now and it will be good for their future.
At the end of the day everyone will be deciding the game wager themselves but I am going to wager on Roma for sure, they have been great this year and Lazio is not really that good sure they had a good 3 game run but if you move it one game back, it becomes 2 wins 1 draw and 1 loss, so 50% win rate with only 7 points in 4 games, whereas rome has 10 points. So, I would say Roma is the favorites not only due to latest results which we have seen si great, but the whole season as well.
Lazio has worse forms than in past season and their problems are too big dependence on Ciro Immobile who is getting older and older. The next derby between Roma and Lazio will be a big clash. It is scheduled on 16 Jan 2021