Ruckus Unleashed is my favorite replacement, with Aruba Instant On as runner up.
One thing i have that often limits my choices is that the ubiquiti's are recessed into my ceiling (6 AP's). I can do the drywall work, if they make the mounts :)
If I have to, I guess i can make some from scratch in solidworks, but i'd rather not.
I do like their WAPs. I've got a couple of RS510 WAPs that do a great job, but initially they had some noticeable performance problems for almost a year until fixed by a firmware update.