Liverpool also have a difficult game against Atalanta, Liverpool is the better team but it would surely be tough. I know many people are already wishing for a Liverpool v Leverkusen final, but there are still so many strong teams that are left in the competition, and if that final is going to happen, the both teams will have to deserve it. West Ham beat Frieburg 5-0 in the round of 16 second leg, so Leverkusen are really up for it in this quarter final game, but i believe they can win.
Leverkusen and Liverpool would be the ideal finals we might see at the end of the Europa League season, but even so the possibility of seeing another team who will be the opponent of one team between Liverpool and Leverkusen is of course still a chance, because as you said at the moment there are still many strong teams who are also eyeing the Europa League trophy.
Liverpool vs Atlanta will be a difficult match to guess because indeed both have so far had a good performance in the league, indeed in terms of quality, of course Liverpool is still better than Atlanta at this time, but Liverpool cannot underestimate Atlanta which has so far also continued to be able to win in the league and Europa League, the lack of statistics of the meeting between the two teams so far makes the results of the two teams' matches will be very difficult to guess.
As for Leverkusen and Westham, so far I think it will be a tandentious where both teams will destroy each other in both the first and second leg, so far Leverkusen went into the quarter-finals casually by beating Qarabag, but Westham came up with a challenge after demolishing another German team (Freiburg)with a score of 5-0, I think it will be a difficult game for Leverkusen, After all, Westham are a strong team in the Europa League at the moment and I think David Moyes will try his experience in Europe to at least make Leverkusen difficult in the match.