La Liga sides knocked Liverpool, Man United and Wolves out of Europe this season. Bundesliga sides knocked Chelsea and Spurs out. 2 French teams made the Champions League semi finals (one of them knocking Man City out). These are good leagues. Neil Warnock teams full of plodders routinely get promoted from the Championship.
I'm not saying we shouldn't sign anyone from the Championship, just that it's wrong to say Championship players are safer bets. They haven't proven that they have enough ability to play in a top league, and so £28m, etc is a massive gamble. Players who have performed well in top European leagues have at least proven that they have the ability required at a similar level to the PL. They're also often very affordable. Kevin Volland is a fantastic striker/wide attacker, and moved the other day for just £15m (just over half what Watkins will reportedly cost!). Yes, they might need help settling into a new country, but that's why clubs invest in player liaison teams.