I thoroughly enjoyed Crime and Punishment, The Idiot, and White Nights, but I'm finding myself slogging through Karamazov. I'm about 600 pages in and its picking up at least. Banking on it all being worth it in the end. Normally I subscribe to the quote "life's too short to read a bad book", but making an exception for Dostoyevsky.
I started with Karamazov, then C&P, then the Idiot. I loved excerpts of Karamazov (The Grand Inquisitor, Dimitry's troika ride, any passage with Grushenka) but I also found it rough to get through. I really don't think I was ultimately able to appreciate it as a whole. C&P felt much smoother and finally I devoured The Idiot. Those novels felt like night and day compared to Karamazov. With Karamazov, I feel like there…
edit: I read the Barnes and Noble translation. And I would encourage reading some passages aloud.