I'm an adjuster. Allstate has a reputation for not paying claims very well.
Example: 2 houses side by side, one with Allstate and one with Safeco. Similar hail damage to the roofs. Allstate will try to cover only individual slopes of the roof where Safeco would cover the whole roof. This is a simplified example, but you get the idea.
Also, much of your claim would depend on the adjuster that actually completes the inspection so any company can leave an insured with a bad experience. But, as stated above, Allstate has a worse reputation in that regard than most.