Yes Motherease One-size (MEOS) are also popper fastening. However they popper to the front rather than the side like Sandys. The good thing I find with Sandys is that you can adjust the waist and thigh separately, especially as I have a baby with HUGE thighs.
With the MEOS you can't really and if I do them up to fit his thighs then they gape on the waist.
Sandys also have a frilled leg and waist which is excellent for Poo containment when babies are still having explosions. This becomes less often after weaning. The MEOS have a bound edge which sits more neatly IMO.
MEOS last for ages. I have some which are now onto their third baby. I have used them folded down from about 4 months and I can still squeeze my almost four year old in one for night time ( he doesn't wet much now).
You can get a popper in booster to use in the MEOS, which poppers into the front when you aren't folding it down anymore. I often put another hemp booster under the popper in booster too if I need.
Absorbancy wise I think the MEOS are probably a bit more absorbent than a small Sandys (mainly because they are a bit bigger so there is more material) and about the same a large Sandys. If you can get hold of any of the bamboo ones they are even more absorbent and so soft, although they take longer to dry.
They also dye really well ( I have rainbow ones now) so if you manage to get some cheaply that look a bit tired, its easy to brighten them up.