Marked bike lanes are better than no bike lanes, but all too often I find they are located right in the door zone of parked cars, which means you get in the habit of riding right near the edge of the general purpose lane.
I really prefer quiet residential streets and rural roads. Nice pavement is a big plus. MUP's are a close second. There's usually too much pedestrian traffic on the MUP's though to really cut loose. Arterials with bike lanes a distant third.
The hands down worst roads to ride though IMO are busy 2 lane rural highways with small shoulders and deep ditches. You find yourself hugging a tiny shoulder, next to a 3' drop, while getting closely passed at 60 mph by drivers that are angry that you are there at all and trying to seize the lane on these roads would border on suicidal.