The both opponents are actually tough opponents so even Tottenham that you are saying that have a better chance of qualifying than Manchester United too can be shock because at this stage of the competition no team is a small team any team that is here should be respected because Bodo/blink has been good through out this competition so I don't think that Tottenham have higher chances of qualifying, but with what I see the possibility of two English finals is high and realistic to me
I am not sure where should I place Manchester United this season. It is impressive to see them fluctuating like waves with such amount of defeats and unstable performance in English Premier League then they did well so far in UEFA Europa League. I can't trust them anymore. Athletic Bilbao is a solid team and if Manchester United played as they did against Wolverhampton or Newcastle United then they will leave from the first leg.
Tottenham Hotspur is another version of Manchester United but facing easier opponent, so better chance of playing the final game. That's all.