We put out a lot of food* for the birds, of varying types, in varying feeders, in a couple of locations. I have to put a disclaimer in that it's my partner that buys the food and insists on it being dished out. Due to her lack of mobility, it's usually me that does all the "admin".
In the back garden, we have a peanut squirrel feeder on the ground, a post with two feeders hanging off it - a peanut feeder and a fatball feeder. Squirrels can get to the feeders on the post but don't go for the fatball feeder. We have two bird tables: a small one suspended from a tree and a large one firmly on a post - the squirrels can get to both of these. As well as that, we have, hanging from a tree, a sunflower seed feeder that, as yet, only the passerines can get to and feed from. We also have, hanging from a tree, a suet block feeder that all birds bar the pigeons can get to. We don't get seagulls feeding in the back garden but we do get, as well as the little birds, jackdaws and wood pigeons.
At the front of the house, there's a large rectangle of grass in a no-road traffic-free cul-de-sac with a pavement around and privet hedges. here, I put down, on the large rectangle of grass and under the hedge, seed and seeded bread pieces.
At the front of the house, it is mainly feral pigeons and jackdaws that feed; under hedge it is house sparrows. In the winter we occasionally get gulls but mostly they don't bother - they're much more interested in food from schoolkids and motorists (as far as I can tell).
In the back garden, the jackdaws will empty the fat feeders quickly - they can empty both the ball feeder and the block feeder in less than a day. They struggle on the small hanging table but still go for it - but not as successfully as the squirrels (they will also knock all the seed off the hanging table when they leave it in a hurry). The jackdaws also go for the large table and any ground food - as do the wood pigeons. They seem to tolerate each other but when push comes to shove, either on the table or on the ground, it's a coin-toss as to whether the woodies or the jackdaws will be triumphant. The woodies cannot manage any of the hanging feeders or the hanging table.
A few years ago, we seldom had jackdaws in the garden. We did get (and still do get) magpies in the garden but no other corvids except for the rare jay. Nowadays, we get about as many jackdaws as woodies - but the jackdaws come and go whereas the woodies just seem to hang around and roost permanently in the vicinity (we often have double figures on our little lawn). The jackdaws are more adept at getting the fat/suet from the feeders but the woodies, as ever, can really get through the food on the ground.
We live on the edge of town - it's more rural than urban. I work in the centre of Birmingham where we have problems with both gulls and feral pigeons - they nest on our roof/in cavities accessed from the roof, and they get stuck in our courtyard (it's too small and the walls are too high for them to fly out of - the older gulls have learnt to go from window ledge to window ledge to get out but the young ones just get trapped there until we can get them out or fate deals them a fatal blow).
In the city centre, it's definitely the gulls that are dominant in numbers and in other ways. I don't recall seeing corvids in the city centre - that might be due to lack of attention but certainly they are too few for me to notice.
So in summary in my experience: in my semi-rural suburban habitat, of all the corvids, jackdaws hardly figured a few years ago but now are up there with wood pigeons and are better all-round food grabbers than the woodies. In the city centre, it's the gulls at the top of the pecking order and corvids hardly make an appearance.
*at least 6kg a week of mixed seed/suet pellets as well as a loaf of seeded bread and varying amounts of sunflower seeds, peanuts, fatballs and suet blocks.
