I have been advised that the most beautiful fjord is the Sognefjord/Naeorfjord. I haven’t seen both, so cannot give you my personal account. But the arm of the Sognefjord that is supposed to be the steepest and most beautiful is the Naeorfjord. It is certainly the most popular one with the NIN crowd.

They are both UNESCO World Heritage sites - an official tossup. I've seen both fjords (and several others as well). My personal favorite was Geiranger. But I don't believe in "must sees". I figure out how much time I really have by computing driving time conservatively. (Some roads in Norway are a bit slow, e.g. speed limit 60 kph = 36 mph, or even lower.) Then I make a prioritized list of things I want to see the most. When my time allocations run out, the list is truncated. As far as Trollstigen being open or not, that will depend on this year's snow depth, etc. Suggest you check with locals or some Government agency such as www.vegvesen.no. I just checked their online road map and Trollstigen shows simply as closed for the winter (no surprise). The NTR website says "Trollstigen is usually closed in October and reopens in May." and "Traffic and road information - Telephone +47 815 48 991." Maybe someone will make a guess for you. I would be amazed if the road to the top of Dalsnibba is open in May, since it is at 4800 feet elevation and Trollstigen is only at 2300 feet. Given your limited time and big desires, perhaps you should flip a coin for this trip and assume you will return for the rest later. Whatever you see will be amazing. Have fun.

Thanks for your feedback.

I am inclining to consider option 1, as i don't think Trollstigen and Dalsnibba would be available in May.

In option 2: i would have chance to explore Stryn/Olden/Olden on the from Geiranger to Undredal
While Option 1: i would have more time to explore near Hardangerfjord on the way to Odda.

Which route is more scenic ?,
Is it still worth doing option 2 considering May time frame ?

I've seen all of these fjords and, hands down, Geirangerfjord is my favorite and far more dramatic. Well worth the effort to get there and the surrounding area is incredibly beautiful. Trollstigen may or may not be open depending on the snowpack. May is a bit early for the higher elevations.

I would say generally Geirangerfjord is usually considered the most scenic and always was the most famous.
Sognefjord is more visited because it is part of the NIN route.
Geirangerfjord is heavily visited by cruises.

I would definitely be concerned that Trollstigen may not open
Based on the chart on the below link ; in 2016 and 2017 the road was closed until end of May
https://www.nasjonaleturistveger.no/en/press/routes-closed-in-winter
Some prior years it would be open mid May though ; so no way of knowing much in advance.