There are plenty of good th8 base designs on here.
I upgrade splash, multipoint, then point defenses. So I do mortars, wiz tower, arch tower, canon. With 4 builders, I keep 3 on defenses and 1 on offenses like DE storage, DE drill, barracks. Then I keep 2 on defenses 1 on Teslas, 1 on AirDef until AD6 then I leave 2 on Def, 1 on Tesla, 1 free for walls.
Base design is good for when you are nearing max TH8 and have 2m+ resources and 20k+ DE, then base design comes into play as that DE assassin the Archer Queen will come calling, not a whole lot you can do but slow her down as she goes for your precious dark elixer.
Most important is to have a farming layout, and do not, repeat after me, do not trap your exposed TownHall. Let them have a free snipe and you get 12 hours of protection from the ArcherQueen!! Nothing worse than losing that hard fought dark elixer.
I've used 3 different bases now as th8 and it is more luck than base as to whether or not you get a lucky snipe or a hungry Giant6 led Archer Queen burglary!!
Good luck and enjoy the game!

