If we're talking April-style unsettled, then I'd go for the warmer option without hesitation. I hate cold outside of winter. If we mean, grey windy southwesterlies however, then I'd go for the cold and sunny option.
At least in a typical unsettled April spell, there is also often sunshine and convective showers with vibrant skyscapes. That with decent temperatures is excellent and good for plant growth.
Getting sunshine all day and a temp below 10 degrees in April is a rare feat in this part of the world and always has been, so I'm not even sure I could choose that option out of pure realism.