My top 5 go-to maps to play are:
Whittleton Creek
Berlin
Dartmoor
Miami
Sapienza or Haven - can’t decide
Worst 3:
Colorado (too restricted)
Mumbai (too crowded)
Bangkok (too few options, too limited)
I’m not sure what else.
Most of the maps outside of the top 5 and bottom 3 are solid middle options. They all have their strong and their weak. I even like Romania for what it is.
Bangkok had so much potential 
Well it depends if it’s the best map or the best level.
So for me :
Best maps
Worst maps
Best levels
Worst level
On the last one, I’m a bit biased because the first time I played the level I conviced myself that it was going to be a “Schrodinger level”.
That is I thought the target had short base routine because once one was eliminated the other would engage in a new one. The closest there is is when Imogen goes to the roof.
best 
paris
berlin
hokkaido
miami
isle of sgail
worst
colorado
bangkok
chongqing
Best: (not in order)
Sapienza
Hokkaido
Colorado
Columbia
Marrakech
Worst:
Mumbai
Berlin
Capathian mountains
Best:
Paris
Mumbai
Dubai
Sapienza
Dartmoor
Worst:
Haven Island
Colorado
Bangkok
Capathian Mountains
Some of the top 5 maps could be switched out with others depending on the day. Obviously, maps like Sapienza or Mumbai are so ambitious and technically impressive. But Dartmoor and Dubai are in the same tier for me due to the amazing atmosphere. I realized that I just really enjoy my time playing them, more so than most of the others.
Also, there’s no level I really hate to play, because this trilogy is basically amazing even at its worst… but Bangkok has too many enforcers/NPC’s, Colorado is not as aesthetically striking as the rest, and Haven Island gets tedious in its layout.
Best :
Sapienza
Hokkaido
Miami
Berlin
Dubai
Worst :
Bangkok
Carpathian Mountains
Bangkok
favourites:
worst:
OK, I can see why some don’t like Colorado (no substantial public areas / different costumes are too similar to each other) or Carpathian mountains (too linear) or Chongqing (quite restrictive outside of the secure data core area), but what is so bad about Bangkok?
I like the hotel aesthetic in Bangkok. The weeping elephants. The fortress where Jordan Cross is located is challenging to get into and out of SA. The labyrinth underground is cool to traverse. There is verticality and poles that are climbable up and down of both sides of the hotel.
Some of the kills are unique to carry out (gassing both targets in the hotel lobby as the bug exterminator, the vegan birthday cake kill of Jordan Cross, sitting in the chair watching Jordan cross freak out with video playback of his killing of his girlfriend, watching Ken Morgan push Jordan off the balcony, being the replacement drummer as Abel de Silva and pushing Jordan over the balcony, killing Ken Morgan with a fire axe in the basement, the Branson MD-2 microphone kill while you are the audio mixer during band practice (the “are we stars” is a catchy tune), killing Ken Morgan by Tuk Tuk explosion and there are lots of coconut tree kills).
Ken Morgan is a boring target and the loop where you serve as the hotel staff and lead him up to his penthouse suite takes too long. Tuppence a wish is by far the lamest challenge in all of Hitman (bouncing coins off a mirror into a fountain)
Overall Bangkok is no Paris in terms of the size, variety and depth, but it is more in the OK category for me. At the time, IOI was making Bangkok while a) Hitman2016 was not selling; b) they were downsizing and were about to be let go from their funder Square Enix.
The hotel just don’t feel like a hotel for me. Half of it is a restricted area, there is no pool or spa area, plenty of rooms, the whole upper level is just one suite which seems a bit much IMO. No access to the beach, the useless garden area………
Top 5 best maps
The 3 worst maps
Kobalt on HitmanForum 
Top 5 best maps:
Honorable mention:
Colorado (great map for contracts)
Top 3 worst maps:
Best Map: Sapienza. The best map, without question. It is the only map with three variations, and has the most interesting use of Elusive Targets that emphasize parts of the map that the main missions do not. Paris may have the most Elusive Targets of any location and may make thematic sense, but quite a few just overlap and feel more like they’re being sandwiched into the location instead of really capitalizing on the space and location they’re in. The Prince and The Guru are how you do ETs: you emphasize them in places that are really off the main direction of the objectives and turn them into deeper puzzles to navigate.
Worst Map: Carpathian Mountains. It exists solely to end the story, and it might be the most linear final stage in Hitman history. Maybe only beaten by Blood Money, but that was more of a spectacle scenario, which redeems it. The only time you’re ever replaying this location is if you’re doing a full storyline playthrough of the game.
Best Top 5
Worst Top 5 (Not in Order)
Just my opinion obviously 
Top 5 Favourite Maps:
Hokkaido
Bangkok
Sapienza
Berlin
Mendoza
Worst 3 Maps:
Haven Island
Hawkes Bay
Isle Of Sgail
My reason for picking Hokkaido and Bangkok is when only H1 was out, i had so much fun on these maps and i still do to this day, in terms of Hitman 1-3 i’d say i still play H1 maps the most.
Haven Island probably wouldn’t be in the worst list if it wasn’t for NPC’s seeing so far and through walls
Same bangkok and haven island very like with hokkaido… i like the hotel and resort style of the game
BEST
LEAST BEST
PARIS / SAPIENZA / HOKKAIDO will always have a special place in my heart 