Spent some time gettingthe best compromise on larger models
the BIG factor was strength to weight
so - the best for me was a 12% root and a 9% tip and the taper ratio was amost 2-1
Effectively a pretty low aspect ratio.
As for the "curve?" (airfoil).
take yer pick- I ran out of ideas on that - an easy shape to make and still not hav flex is important
so I usually made the LE a small radius (strong ) went to a blended high point at -oh 25-40% of MAC and then straight line to a blunt te a long as it didn't twist easily, I never could find a dimes worth of difference

So-looks good , survives threshing about. for really small stuff - flat plate -no question about it tho some who don't fly em will disagree. (n come up with some old formulas etc-to try and make their point )
From these to the previously mentioned 12/9% stuff - the compromises were for strength
The hard point for some to swallow is that the shape used on MOST aircraft evolves from strength needs - not some L/D calculation.
It's all necessary but strength comes first
max strength with min weight then drag
got it?
With the advent of Depron - we got extremely high strength to weight -cheaply -and tis allowed for a LOT of cut n try which prooved the point.
I still get guys asking " yeh but if you could streamilne that flat plate - wouldn't it help?
In the manner n size of use
the answer is simple
No
There is yet another approach
a big fat airfoil say 18%- made in an extremely well thought out fashion for min weight -
this setup is pretty numb to AOA and has been used on control line stunt for 60 years I know of - and on a truckload of flip n flop lawn darts etc..
My ERATIX is like this and is a lot of funto fly mainly because it is supe light - 600 squares and 3.75 lbs all up.