BA is not exactly setting the bar very high when talking about pilot salaries, let's be honest.
We are talking about the best contracts in Europe in this thread, and 4300 gross might be average in the f***ed up state the industry is in the old continent, but should not even enter the discussion when talking about the best conditions.
We could write pages on what each of us consider the minimum acceptable for this job, but considering the investment required, the amount of stress, fatigue, the continuous checking and training required, moving from one side of the world to the other, personally I would not be happy to accept anything less than 4000/4500 after taxes plus pension and benefits, and that's for a FO without that much experience. An FO with 10 years of experience or more should look for (much) more than that, obviously.
I am not saying one should refuse 4300 gross a month as first job, but settling on that kind of money, and considering that good and industry-leading conditions, that's another story, and probably one of the reasons things will not improve anytime soon.