ktchong: If you are looking at classic RPG series from the 1990s:
You did not mention Quest for Glory. Quest for Glory was, IMO, the best RPG series from the 1990s. There were only five games in the series. The creators originally planned the entire anthology to have only four games, later an additional game (the third game) was added in the middle to improve transition between the second and fourth games. As the whole series were planned to have an opening, a middle transition and an ending from the start, so the whole series were very consistent and well executed, with many recurring characters and themes, and a few story arcs and plots that span the entire series.
Ultima is the second best, my personal favorite, but the first three games are unplayable. They are just way too old, so skip them. The "Ultima experience" really began at the fourth game, Quest of the Avatar. Games number 4, 5 and 6 make up one trilogy, (i.e., the "Age of Avatar" trilogy; the story of the three games centered around a few unified themes.) Games number 7, 8 and 9 are another trilogy, (the "Age of Guardian" trilogy.) Number 7 are the best in the series, and number 7 includes two main games and two expansions. Number 5 and 6 have fan remake versions, which use he Dungeon Seige engine and, IMO, are more suited for contemporary players than the original 5 and 6, which are becoming a bit outdated.
I do not particularly like Might and Magic. Number 6 is the most acclaimed in the series. Numbers 6, 7 and 8 make up the final trilogy in the series. The best Might and Maigic games are actually not the RPG. The bests are the turn-based strategy series: Heroes of Might and Magic. I'd say skip the RPG and play the Heroes series, which have very strong RPG components.
I have never played Arena so I can't say how it is. However, I hated Daggerfall. Sure, it has a gigantic world and thousands of randomly generated dungeons, towns and locations; but everything in Daggerfall was so generic. It may have thousands of different towns, but they all look and feel the same -- as they were all generated using the same basic models and building blocks with absolutely no variations. The same goes for dungeons. The game may be huge, but it does not have any... heart. The whole world just felt very generic and dull.
Well from what I have seen Arena is more generic, all the provinces you visit like Morrowind to skyrim looks the same, so no mushroom trees in morrowind.
And I always prefer Daggerfall and I am glad I am not the only one, Arena looks too dated imo where daggerfall looks as the though its more modern for the better.