State of Javascript client side error tracking

I made a rant about javascript error logging state of the art :

1. Interesting Hacker News discussions -
a) Rescue.js : Not in production now, but thread is interesting to read -
https://news.ycombinator.com/item?id=4653272
b) How to do it with google analytics: https://news.ycombinator.com/item?id=4875841

2. Products and methodology -
a) Sentry : Looks very promising but not free :
https://getsentry.com/welcome/,
https://github.com/getsentry/sentry
b) A YC startup around it : Proxino https://www.proxino.com/ ( Yeah ssl certificate is expired, looks like guys are not in action )
c) An another MVP around the idea : http://www.errorify.com/features ( looks like dead to me )
d) Old school way : http://mattsnider.com/window-onerror-event/, http://mattsnider.com/catching-all-javascript-errors-in-all-browsers/ ( Warning try, catch ahead )
e) Clicktale : http://www.clicktale.com/

3. Looks Promising -
a) Airbrake : Looks promising ! Read here about their state of the art : http://airbrake.io/blog/notifier/state-client-side-javascript-error-repo...
b) Exceptional : http://www.exceptional.io/
c) And of course Errorception: http://errorception.com/