Hi, again, Adelle,
For m, the clear winner here is the Bugaboo Butterfly for sure. The Yoyo Plus is once in durability, as the frame is sturdy and well made, but that is the only advantage for me personally. The Butterfly has an incomparably longer, roomier seat (Yoyo's seat back is very very short, as opposed the 56 cm of the Butterfly) that is not as crazy slanted in the most upright position as the Yoyo does (god, when I see those 5 months old babies in the Yoyo half not breathing because their head is falling forward I want to cry). Overall, the comfort for the baby is much higher in the Butterfly (leg rest, more recline, longer seat, seat insert, better hood), and the space in there is also much better thought of. So there is no competition here, really, not for me - I personally would not want my kid to be sliding down, hanging on the harness in the Yoyo.