Admittedly it was an Orange San-Francisco (AKA ZTE Blade).
I didn't like the Orange bloatware/GUI it came with, so within 12 hours of opening it, I'd rooted it, unlocked it, and stuck the latest Cyanogenmod on it.
Since then, every phone I've owned has had Cyanogenmod put on it within a day of receiving it.
Being a tightwad though, when I accidentally washed my SF, I bought a 2nd hand HTC Desire off a friend at work, then when another friend realised I only had a single core phone, gave me his old cast-off dual-core HTC Sensation XE that was gathering dust in a drawer.
My daughter received her 1st mobile (Samsung Ace 3 - I know! I wanted to get a Moto E, but "Selfies are important"), and she immediately asked for Cyanogen mod on it, as she was used to using my old Desire. Once it's out of warranty, the excuse for an OS will be removed, and something sensible put on it!
My next phone (assuming I don't get any more Pity Phones) will probably be a Moto, running vanilla Android, which is just how I like it.