My gf learns French. Courses are quite expensive in Geneva or in general. I know there are online classes from other countries that are much more affordable. Would you say it's still better to attend a class in person?

There's a class of one month that costs 1'050.-, in Geneva (IFAGE). I think it's better she attends such a class at the beginning so she can meet other people and get lessons from native speakers. It costs more than for example a class of 3 months in Peru that is 100.- per month for three months.

The time per week is the same (3h per day), it's intensive but it's online. I think you miss quite a lot when you're studying from home. But I might be wrong.