I use a Nest... which was a gift. This along with the Ecobee apparently are more snazz pizzazz than typical thermostats. The Nest also apparently can suffer from inadequate powering due to its power stealing feature not getting enough power to fully charge it, as well as apparently some crazy internal power struggle... but it's not bad if you can find it below $250 (Black Friday/Cyber Monday?).
As for hacked IOT, no idea.
https://www.upguard.com/blog/7-hacka...or-at-ces-2016
Per this, thermostats aren't on the list, but that's not saying the Honeywells can't be hacked. I've often heard good things about the Honeywell thermostats, most say they function well, but aren't as pretty as the aforementioned thermostats. (It's a thermostat, not an art piece! ... I might be wrong about that though)
http://www.networkworld.com/article/...you-think.html
This article mentions a Honeywell wifi enabled "hacking"... but it's not really a hack. Just some jilted lover who had the password to access the thermostat and started messing with the ex. The article mentions that as long as you change the default login information of the device, you're pretty well protected (as can be) from being "hacked", then goes on a schpiel similar to the "don't set your email password as 'password' or '123456789'" articles. The article even mentions Nest as being somewhat resistant to IOT, but nothing is immune to IOT.
Unfortunately, other than telling you I think the Nest/Ecobee bad if you can get a decent deal on it, the Honeywell do seem well regarded, and the IOT concerns on them doesn't seem to be a big deal.