I've only used blucon in an android context with xDrip+, and a Fossil androidwear watch, and that certainly works pretty well.
If you're talking ios and apple, I've not used those, but it seems that blucon works with Spike, which is designed for ios, but I don't know what level of watch integration it has.
https://spike-app.com
@Mel dCP recently posted that she had installed Spike but was waiting to order her blucon - Mel, any chance of posting some screengrabs of Spike's watch integration pages?
In passing, it seems that Ambrosia has recently redesigned blucon to make a waterproof version at $165, compared to the non-waterproof one at $110. It's an option on their order page. Haven't tried it, and haven't read any reviews, no idea how waterproof it actually is.
Apart from blucon, there's another libre transmitter recently popped it's head up, miaomiao, which is advertised as compatible with both the android xDrip+ and the ios Spike:
https://www.miaomiao.cool
It got a good write up on a T1 facebook site but the reviewer had only been using it for a couple of days.
There's a lengthy and very technical thread at link below between the makers and the xdrip developers trying to iron out some technical issues. I've not used miaomiao myself, I'll probably buy one at some point out of curiosity, but the impression I was getting from the thread was that it was still a work in progress, so might be glitchy in the real world. Unlike blucon which is slapped right on top of libre, miaomiao is separate and hovers over libre, and there seemed to be a bit in the thread which suggested the "air gap" between the two made a difference. A simple thing like that is the sort of basic thing which might screw it up in the real world.
https://gitter.im/miaomiaoSDK/Lobby