Hmm...didn't the legendary edition of oldrim had all dlc? Anyways, I'll suggest SE, since it's more stable. Frankly, I don't play SE, since a few of the mods (race/compatibility, etc, etc) that are completely indispensable for my playthroughs aren't converted yet to the new one, not sure if they ever will. I do suggest SE since the instability/maintanence of oldrim can get grating. However, If you don't mind that and want a bigger library of mods, then try the old one.