XEM or really any other blockchain today isn't as secure as BTC because the tiny size of their network make it vulnerable to things similar to 51% attack...
detractors of BTC would point out that a lot of BTC nodes are in China, which is not a good thing either.
on the specs side, XEM and many other blockchains are superior to BTC.... XMR has stronger anonymity, ETH has smart contracts, etc...
I suggest you take a thorough look at NEM white paper before making such claims. NEM is full of security features that don't exist in BTC. Especially the node reputation system and time synchronisation feature are things that truly matter when talking about security. Also look at PoI consensus while you're at it.
I'm far from worried about a 51% attack due to node reputation system and PoI, but feel free to describe a viable attack scenario if you have another opinion.
Most of the claims that are made when comparing security of alts against BTC is based on feelings. I personally stepped away from the subjective analysis and studied the available documentation, which made me come to the conclusion that NEM is probably one of the most secure ( if not the most secure) chain(s) in existence.
Until someone comes up with solid evidence to refute this I'd say it's all FUD!
Both Factom and Apostille probably have their pro's and cons , but I wonder if any of you have really looked at NEM and Apostille white papers before writing it off as inferior to what Factom has to offer.
By the way XMR's anonymity might be something that is highly appreciated in the crypto community but has little added value for real world applications IMO and about ETH smart contract feature; we've all noticed how superior that has been recently