KSA stands for Knowledge, Skills & Attitude. It's a half assed idea that the schools certify that you are "fit to be a pilot", whatever that means, so whenever you reach your airline you are allegedly warm and fuzzy, but it opens up a whole legal minefield, especially as some schools don't have staff qualified for such assessments. Luckily, I'm a CRMI..
I've never agreed with it, it's an unnecessary burden on a small school and should be done by the airlines anyway (if they want particular candidates, they should select them). There was great hilarity at the KSA meeting in Koln when I said that we teach our pilots to be anti-authority
Our KSA assessment is done over the consolidation periods, together with timely paperwork.
To answer the OP, BGS is one of the best choices.