Norway: Bergen vs. Trondheim vs. Alesund vs. Stavanger
 

Which city should we base ourselves in if we like day trips and nature/hikes (easy hikes only)/fjords and have only 3 full days? 5 if we include transfers. We can rent a car if necessary. We just don't like lugging our luggage around and changing hotels frequently so just having one base would be ideal. We are going in mid-late September 2023 and staying for 3 days in the chosen city before flying to Lofoten for another 3 days. Thank you!

I think that Bergen offers more choices for excursions. You could even do the Norway in a Nutshell tour one day by taking the train to Myrdal and take the rest of the circuit to loop back to Bergen.

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Bergen itself has more to offer than Trondheim or Alesund.

I think you should go to Bergen. In addition, Bergen is the second largest city in Norway. Be sure to see the area of Bruggen, famous for its small colorful houses. Just 150 meters from Bruggen, you can take a funicular that will take you to the top of the 425-meter Mount Fleyen at the moment.
Not far from Bergen is the second longest fjord in Norway, and you will not have any problems getting to it. There are also many museums, churches and unique buildings that you will definitely be delighted with!

Ålesund has the prettiest location and is closest to the most dramatic fjords. Trondheim is interesting but not fjord-y. Most people will say Bergen because it is the most popular.

Ålesund has direct flights from Amsterdam and probably Frankfurt.

Åndelsnes is not mentioned and suffered a lot war damage so charmless, but probably is the closest to meeting your needs. Can be reached by train from Oslo.

I have not been to Bergen, Trondeim, or Stavanger, but I adored Alesund. It was not easy to get to but we took the ferries, which were marvelous. Talk about scenery. We started the Norway in a Nutshell from Oslo but got off at Balestrand and spent the night there. From there we took a ferry to a lighthouse (in Maaloy), stayed at the lighthouse there, and then took the ferry to Alesund. From Alesund, we took the train somewhere (Andalsnes/Dombas was on the route). That train journey was spectacular. It took us four-five days.

The lighthouse we stayed at was called Ulvesund Fyr. There is a more famous one nearby - Krakenes Fyr. IIRC, we took the ferry from Balestrand to Maaloy.

I really liked Balestrand as well.