Ubik and Dick? Is there anything else like Dick? If you liked Ubik, you'd probably like The Three Stigmata of Palmer Eldritch and A Martian Timeslip. They're not my faves, but they are wacky like Ubik in the sense they mess around with realities in a similar way. My fave is probably The Man in the High Castle.
You might like to try Stanislaw Lem, but it's heavy. The most famous and possibly the best is Solaris. Lem loved Dick, if you see want I mean. He called him 'a prince among knaves.' He annoyed most of the science-fiction writiers in America, particularly Philip Jose Farmer. It's called the Lem Incident if you want to google it.
You got me thinking. If you like wacked-out sci-fi with mess-up realities, try some Christopher Preist. I reccomend The Prestige and The Separation. He really pissed off Harlan Ellison, but that's another story, lol. I just read the Inverted World by Preist and I was really impressed by it. But the other two I mentioned first are more wacked-out in a Dick sense. If you know what I mean