The strength of these two teams is relatively balanced but I am sure that Roma will be able to win the 1st leg which will be held at the Olimico. The Jose Mourinho factor is clearly more of a consideration for the Giallorossi, he has qualified experience in Europe but it also depends on the Roma squad in which the match is played, meaning that none of Roma's mainstay players are seriously injured.
I agree that two teams have same quality but I disagree that AS Roma will surely win at their home stadium. A home stadium is an advantage for the host team but it brings pressure to their players too. Because of similar player quality, anything can happen at home stadium or home-away stadium. Just a mistake from player or referee or an excellent strike from one player can decide its result.
Roma's seriousness was seen when they played the second leg when they were able to beat Feyenoord into extra time. In normal times, Mourinho's men almost had to bury their dreams, but The Special One was able to motivate his troops to catch up and force their visitors to recognize the greatness of Roma. Alonso certainly has to learn from the number of games played by Roma, otherwise he will become the next victim of Mourinho's cunning.
If you use the match with Feyenoord as an example, you should say how Roma were very close to a defeat in that match. Dybala saved them with a late goal and in extra halfs, they suddenly destroyed Feyenoord but in 90 minutes, that match was very equal for both teams.
Mourinho is more experienced than Xabi Alonso and Roma will have to hope that Mr. Special will choose a good tactics, good squad to help Roma gaining advantage from the first leg match.