I've got ER32 chucks for my MW Lathe and Mill. I've also got ER32 collet blocks and a spinindexer that takes ER32 collets.
There's a lot more stuff in ER32 than any other size so it was a no brainer really, especially as the headstock bore is only 20mm on my MW Lathe.
I bought a little ER20 chuck for the Wood Lathe though as I already had some collets, the bore is only 10mm on the Lathe and the chuck only cost £6.96 posted from HK. I would have got the 32 but it was three times the price and I'm trying to save some money at the moment!