Worst map for my playstyle? Luxury resort is the winner here. One alien often spawns on the roof overlooking the dropship, ready to rain fire or grenades down, doubly worse if armed with a plasma blaster. You have 3 lines you can assault over; one leading up a doubling back stairway to an exposed semi blind alley often with aliens just around the corner overlooked by 2nd floor windows, one leading to the centre of a map through a basement which you exit towards the already mentioned blind alley or to the third line of assault, which is a small stairway leading to a wide open area overlooked by alien firing points in ground and second floor windows. Other aliens spawn in good cover behind buildings far from you, and will pop out of cover as soon as you leave troops exposed. My only successes on this map have involved lots of reaction fire luck with shotguns and my own plasma blasters, liberal use of fire and smoke, and more than one melee kill when things get desperate.
Honourable mention has to go to the secret depot, which often has a number of aliens in firing positions overlooking the automatic door triggered by putting a soldier there as a reaction fire magnet. Smoke can make their survival more probable, until they rush the door, or an alien appears on the roof above the door and wipes your squad with a grenade, plasma blaster fire or some fully auto rounds of some sort.
I have also recently begun to hate the archaeological dig. There are so many points a single alien could entrench themselves and be a right pain in the ass.