Single bed or double

Hiya at the moment my 2 wee boys like to have a cuddle before they fall asleep and its usually in my bed, ive been trying to get them to sleep in their own beds and my oldest son at 7 currently has a single bed and my youngest who is 3 has a toddler bed, do you think it would be a good option to get a double bed for them to share or another single and a single each not sure what would be best , anyone elses share a double bed? Thanks