my favorite economical equipment is my skipping rope: $ for use, there isnt anything better out there.
in terms of strength training, i have grown fond recently of one-handed dumbbell military presses, but id like to have access to a barbell so i could complement it with deadlifts and barbell rows (and two-handed military presses). without equipment, i like russian twists a lot, but havent done any in quite some time.
the gym machines i favor are the lower back extension machine - maxed that one out easily - the calves machine and the leg press.
my favorite allround exercise equipment probably is either my heavybag (plus bandages, gloves,...) or thai pads. for more solitary moods, i prefer the heavy bag, but if the social batteries allow for it, i prefer having someone drive me with pads, as its so much more intense and variable.