From my personal experience, (from easiest to hardest):
(1) QM2,
(2) Cost and Tax Law,
(3) IFA2 and Business Finance.
It's just me, though.
I know this is not true for some, but my friends and I actually did way better in QM2 than in QM1, although QM2 is basically just an 'extension' of QM1. The problem with QM2 is that there are many topics to study - from simple parametric and non-parametric tests to regression, logit, and ARIMA models. The good thing about it is that it doesn't dwell too much on one topic, as opposed to Intro Econometrics where the whole subject is all about regression-based models. That said, QM2 can definitely be aced with consistent effort.
They say QM2 is easier taken in Summer, but I wouldn't know since I did in a regular semester. But if you're not confident enough, given that you struggled with QM1, just take QM2 in Semester 1 and take IFA2 (or Business Finance) over Summer.