The Stone Roses debut is the obvious one as, with the Happy Monday's Bummed from the preceding year, and several 12" singles it defined the Madchester scene. I'd prefer to pick something more club/techno/electronic though as that is what was really breaking at the time, but it was a 12" culture, not album (all the landmark Warp, Superstition, Harthouse etc albums came out a couple of years layer). The best I can come up with off the top of my head is 808 State's Quadrastate mini-LP on Creed Records as that indicated the direction of travel for sure. Over the next few years 808s, 303s etc were bleeping away in the better clubs across the land. Like many 1989 was the point I jumped ship from indie/rock to electronica, hence my choice here.
PS I played on an indie album released in 1989 (
link)!