I opted to do a self assessment as then I have more confidence that everything is correct. This is partially because I pay into a personal pension as well as a work pension and it allows that to be taken into account. If you do not have complex accounts a self assessment is easy to fill in these days.
Personally I'd rather leave it to them but I don't think I'll have much choice next year. Thus far in this financial year I have received 7.2k in interest, I estimate that I won't hit 10k mainly because the interest rates for the last financial year (to be paid in this financial year) were in the 3.5% region, where I can I have opted to reinvest in one year fixed savings at rates ranging from 5.85 - 6.06, those figures will push me over the 10k rate and I'll have to do self assessment. The same for my wife; all our taxable accounts are held in joint names. I've just opted to settle the amount I owe HMRC rather than them adjusting my PAYE figures.
I'm glad you find SA easy. I'm dreading it!