Actually, wrong, because best signal doesn't automatically correspond to best performance. 2.4GHz networks have further reach and penetrate walls more easily which probably means you'll get more bars of signal (pretty BS measurement, but for illustrative purposes it'll have to do) if you have a large domicile - but for that very reason it also leads to more crowding in the airwaves when different networks overlap.Wrong. Same names is the way to go. iPhone will pick the one with the best signal automatically this way.
You also have only 3 completely discrete channels in the 2.4GHz band, leading to even more crowding, especially as some people unwisely use those channels that overlap other channels, causing even more crowding.
Unless the signal is so weak you can't get a reliable connection at 5GHz you will almost always get better performance in that band than at 2.4GHz (due to things like more capacity due to higher frequency, and also more discrete channels, none of which overlap each other.)