The differences arent as great as between linux distros as the core components are the same with AROS distros (so far). Although I dont use either (I use my own system) I'd probably be more inclined to go with Icaros at the moment, for no reason other than its been in development a lot longer and is probably a little more mature because of it. Having said that though Broadway is more active latealy, so it might be a better AROS experience for the latest and gratest developments. Both will probably require a little tweaking to get working as you like (as is the nature of amiga based oses), so I dont think it'd make a lot of difference.
As for waiting for more gfx drivers with full support, AROS does have the most hardware support of any amiga os system by a long, long way. You'll be waiting a while if you want Windows level support.
Now as for usb keyboards, have you enabled legacy usb support in the bios? I had the same problems as yourself until I did that and now its fine.
