To judge from quote numbers in packages most advisers choose to start an insurance package with life cover. That choice might be worth exploring in more detail later on - but for now, let's move on and think about what comes next.
The most common addition after life is trauma insurance. In the past trauma has been criticised because, being condition-based, it is possible for a person to suffer a disability and be unable to claim on their trauma. Those folks argue that income protection should be bought first, and trauma afterwards. But trauma advocates have much the same argument: they point out that you can be diagnosed with cancer and not qualify for income protection. Trauma provides options at that point which income protection doesn't.
In a perfect world you would buy both. But budgets are rarely like that.
In total, Trauma is currently quoted twice as frequently as Income Protection. So where it is a straight choice, Trauma is winning.
More interesting is that two thirds of IP (including repayment protection) is sold in combination with Trauma. So there is a significant proportion of cases where advisers are successfully selling both, but when the chips are down, trauma wins. This must mainly be about budget, and some of it is about presentation.