I have owned both iOS and Droid OS now, even at the same time. All I can say is ended up hating droid so much b/c of the amount of bugs and crashes I dealt with. I had at least 10 forced system restores within 6 months of owning the droid. While it has improved dramatically since the pre-ice cream sandwich days, i still feel that they are not up to par with reliability. I quit after 8 months in my contract and went with an iPhone.
The one thing i HATE about apple is the big brother-like restrictions, and the crappy thing is in terms of hardware anything apple will never be the newest/best/most-up-to-date ever but you can count on it always working. The one thing I do believe is great with iOS is a jailbroken (JB) iDevice. It will beat anything hands down any day! I LOVE my iPhone 4s JB on iOS 5.1.1. I get the best of both worlds: 1.) An OS/device that always just works and 2.) the customizability of that OS to my preference. If I do install any tweak that doesn't work/causes a crash it boots into safe mode, I uninstall, and im back to normal. Its simple to figure out, and will be about the same learning curve you get when switching OS's
Honestly, I'd go with an iP5 and JB iOS 6 asap. While this is still impossible at the moment, the devs literally only need 1 exploit and it'll be done with. If not, it'll still be a better option to me b/c of the amount of apple products I do own.
I guess it'd be worth it to check out the newer mobile OS of Win 8, but I didnt like the one before it much and I don't care for the tablet experience of the same OS either (But i dont like tablets in general).
As for the flash issues, there are definitely 3rd party web browsers that allow flash and function like they say. Never had much of an issue with flash stuff, but i guess I hardly need it. (Sidenote: The Chrome for iOS is my favorite!)