The biggest winners were the centre-right (FDP) and right (AfD), but smaller gains were also made by the Greens and Die Linke (Left). The governing coalition suffered a huge drop in votes, with the SPD losing out badly: they've now gone into opposition, probably because they realise they could be extinguished as a political force if they continue to support Merkel. Much of the pre-election debate focused on race and immigration, although the AfD had no TV debate presence. In fact asylum applications have dropped considerably and Merkel has toughened deportation rules. Interestingly though, in a survey of AfD voters*, some 55% said they were uncomfortable with their policies but voted for them anyway, so it remains to be seen how much of their increased share was the result of protest rather than ideological commitment.
*
http://wahl.tagesschau.de/wahlen/2017-09-24-BT-DE/umfrage-afd.shtml (for any German readers on here)