Bosniaks just elected a centre-left party to office, so any nonsense that they are not secular is nonsense. Yes, jihadists did manage to recruit a few people, but by and large they failed to establish political power and most of that generation was extinguished by the end of ISIL's caliphate.
Bosnia is quite secular but still more religious than say Albania or Azerbaijan but compared to most of Muslim world quite secular so I think putting it in top 5 and even Kosovo as well makes sense. Mind you Bosnia is only barely a Muslim majority as Serbs are 1/3 and they are mostly Orthodox Christian while Croats who are 1/6th mostly Catholics. But from what I have seen little evidence Muslim population is more religious than Christian.
White Muslims in general tend to be more secular and same is case in the Ural-Volga region of Russia. Caucasus is one exception where white Muslims are more religious, most notably Chechnya. In many ways Bosnia, Kosovo, and Albania may be Muslim but they are culturally European. By contrast Turkey is more a blend of European and Middle Eastern culturally sort of acting as a bridge between two.
At same time lots of Muslim countries have centre-left governments but they are usually considered centre-left due to economic policies not religious ones. In Muslim world left wing governments are types who nationalize major industries and believe in more redistribution of income but not necessarily socially liberal like centre-left parties in West are.
