Stub Cill or not over concrete

[Anak]

I am getting new windows in the front of my house and am not sure what to do about the cill.
Originally I had planned to get windows without any cill and sit them on the concrete one, when the fitter came round to measure up he suggested fitting an 85 mm stub cill.
He said he believed it would look better as there would be not drain caps on the window which discolour over time and that it would also mean there would be no large visible bead (or fillet) across the bottom edge of the window (as the concrete one is not level).
For context the cills are very rough pitted / bumpy concrete (100+ years old) newly painted white, they are on the tilt about ~15mm out of level over the 800mm width (window heights are 1500-1800mm).
The concrete cills protrude about 5cm past the house brickwork, are quite high (maybe 20cm) and are on a gentle slope, I am told the stub cill should not pass the house brickwork.

Can provide pictures of how it is currently if useful.

 

[crank39]

Stub cills all day long for me, just ask how he's planning on sealing the stub cill to the concrete, will he still put a trim across the bottom scribed in of course or is he going to point under the cill? Also make sure he seals the joint between the window and the stub cill when he sits the window onto it and seal the ends off to stop water running sideways and causing damp patches to the bottom corners to the internal plaster

 

[Anak]

Thanks for the input, went for a wander round today to try and find some examples (did find one that looked alright), to be honest I never considered a cill before the guy mentioned it to me.

 

[Gazman16]

Stub for me too.
Face drain caps look awful and stub allows you to make the window larger.
Without a cill you have to make the window small enough to fit in the hole (assuming render either slack on the height or the width) with a cill you can go big both ways, Shuffle the window in width ways then lift it and slide the cill in under.

Any gap cill to cill over 10mm render and paint the same color as the concrete.