Hiya, Seni,
Wel, and how old is your little one? As the answer quite depends on that, and perhaps the "how does he/she like to nap"? I mean, my third, for example, hated a full recline and fell asleep only if I reclined the seatback partially. The moment I put the backrest to a lie-flat, he woke up. He was a bit older at that time, about 1.5 years, and as such, the BGB Buttefly would suit him much more. The Butterfly sports only a partial recline, and for some (especially with very small babies, like under 6 months of age), that is a real breaker.
Overall, the Buttefly is higher quality and with MUCH taller, 56cm backrest, so that will be a huge advantage for long-lasting use even with a larger toddler. So my personal choice would definitely be that.
However, if you have a small baby and/or your little one needs a lie flat, you will rather go with an Anex. The Anex Air-Z is better if your baby is really a small, small baby, as it can face the parent of sorts, which is useful with small babies. However, the Air-X is a bit more spacious - the seat feels longer, and also has a longer canopy, so if you don't need that reversibility feature, I would rather take the Air-X than the Air-Z (the differences are, other than that, rather small).