Interesting thread this one...
I always use home-made chicken stock in my base, stock cubes are rubbish in my opinion and just don't produce a good flavour. I make a stock with the left over carcass of a roast chicken, containing peepercorns, (a little) star anise, bay and cloves. I would normally add onion, pepper and celery but there is little point if those ingredients are going in the base also.
I always add a stick of celery, and I think it makes a difference. I also add some carrot and green pepper, but I made bases that are just as good without them.
I agree completely with the remark that currytester made about never getting good results with 'off the shelf' garam massala, I don't it in everything, but I do think home-made is much better.
I used to belive firmly in the importance of pre-frying, however now I'm not so sure! having tried making base without initially frying the garlic/ginger/tomarto first, and it seemed ok. Also I wongder if if is evfen necessary to fry the spices, provided oil/ghee (or some other lipid!) is present to extract the flavour. In some base recipies here the spice is simply added to the base with the oil, at leat that way the temp can't climb above 100c and the spices won't burn!
I use amethod that is a bit of a distillation of many on here. Boil; chopped onion/celery/pepper/carrot and stock, then after an hour or so fry garlic/ginger paste a few minutes in oil, add blitzed tinned toms, fry another few mins, add spice mix fry a minute, and then add the fryed mix to the reast of the base, bltz the lot, cook and skim for 20 mins or so.
I think currytester is right in his opinion that if the base tastes like a good (albeit slighty spicy) soup in its own right then it can be the basis of a good curry. I still believe the success of the final finished dish is more down to the on the ingredients and techniques used in the final stages, and this is far more important than minor differences between base recipies!