You put down Brand way too harshly. He E is not skillful at all? MOST people do not ever remember what his E does when champions are ablaze. It should be common sense, but the fact that it creates AoE and passes his passive onto multiple targets in a teamfight is very strong especially against tanky teams.
Usefulness aside, I personally find Yasuo easier to use but not easier to learn. His windwall is really his only worry. He has in lane sustain, he has mobility, his ult cast range is very far, he has conditional CC on a third low CD cast that's not circumvented with tenacity, then he gets double crit and passive armor pen.
From those it assists him so that his builds can revolve strictly around damage, so he can play aggressively in lane and not worry about ganks, and he is very safe to play with his shield and wind wall to block anything that travels. It's all very safe if you have an idea of how to play him.
Brand may be more basic but he has a lot more to worry about. He has mana, his cooldowns are very high, his mana costs are high, his AP ratios are crap so building AP feels weaker than most, he has no mobility, you need to get in melee range to land an E Q, or no blockage to land a W Q. And then he has more options available to him.
For Yasuo there's poke with Q when stacked, Block damage with Windwall and then Dash for extra damage and to build flow. He doesn't have much versatility to his kit ironically for all that it has.
If you can poke with Q, you can nuke harder with W. His ideal teamfight damage would be QEWR, for AoE pain, whereas most would go W Q E R...W. The damage is far lower in the latter. Then you need to focus on his passive always being up, so timing your skills apart.
-- Technically Yasuo is hard to use, but once you get used to it, he's not at all. Then you either feast or famine against gradually more competitive opponents.
-- Brand is very easy to pick up, but you must constantly be getting better at planning to make him work against better opponents.
