An up to date OS isn't critical to everyone , but with the average mobile phone contract being two years and a new Nexus phone going for under £300, I'm not that interested in buying branded phones for up to twice the price. Especially when it will be obsolete in little over a year
http://www.theverge.com/2013/7/2/4486950/htc-confirms-one-s-no-android-sense-5-update
Sent from my Nexus 7 using Tapatalk HD
That's pretty poor from HTC, you shouldn't have to root/custom ROM your phone just to stay up to date.
If I were to buy a new phone right now it would be the Nexus. I'm happy with my S3, and Samsung are pretty good at keeping it up to date (it's getting 4.2 and a bunch of S4 features delivered this month), but the price and the fact it's updated directly from Google make the Nexus the best buy as far as I'm concerned.