Ancestry....do not always record things correctly, as they have no permission from Scotland to record data they rely on researchers who are tracing their own families, who may well have the wrong information ; so that people who are also looking for that information cannot correct the original mistake by others.
Ancestry are far from perfect - but nor are FindMyPast, TheGenealogist, etc.
When it comes to Scotland Ancestry are far the best subscription site as they have census transcripts (yes there are plenty of errors) - but none of their competitors have anything to match.
Of course ScotlandsPeople (pay per view) have pretty much got Scottish family history sewn up - at a price.
FindMyPast have the 1911 as an advantage (though I expect Ancestry will have it in six months or so). The subset of the FHOL data that they could be useful, but very patchy (my ancestors have pretty much avoided being included).
TheGenealogist has PCC wills as part of the subscription package, and the images are significantly better than those on DocumentsOnline. If you want a lot of these wills its worth subscribing for a period. Their searches are also more flexible.
However, if I was to go for only one subscription it would be Ancestry - they simply have more than anyone else. If Brightsolid include the BL newspapers in the FindMyPast collection I suspect I would opt for FindMyPast, but I suspect there will be a new newspaper subscription site rather than an enhancement to FindMyPast (hope I'm proved wrong).