What're you doing to your iPhones? I end up holding on to mine for 3+ years each because I can't kill the damn things and it feels so unnecessarily extravagant to upgrade more often.
Follow-up– if all these problems are necessitating yearly upgrades, why aren't you getting your phones fixed under their 1-year warrantee? Batteries, stuck buttons/switches, charging ports, etc. should all be covered.