I agree that the cantrips arent that great on a pure bladesinger, which is too bad. As I said, pure bladesinger is better off being a spellcaster that has amazing defenses and concentration when needed. To really make the cantrips shine, you need some multiclassing (or to be an EK). For pure bladesinger i think green flame is superior to booming. It scales with int and its easier to get the 2nd target than to proc booming blade without some cheese.
So our winged feral tiefling booming blade guy will probably not be a pure wizard, but its still a good race choice.
Also, a winged feral tiefling any other school also works great.
In terms of heavy armor melee wizards, I think only way i would do it is with warcaster and substituting a int based cantrip for my attack. That was an okay build until the new cantrips came along and made it irrelevant.
Alternatively, just wearing heavy armor and hanging out in the back and using ranged cantrips also works. Then you can just take the -10 speed.