For the five gifts of Terumah Gedolah/Terumat Maaser/Maaser Rishon/Maaser Sheni/Maaser Ani:
Chochmat Adam (Shaarei Tzedek 10:13) writes that the relevant blessings are Lehafrish Teruma/Terumat Maaser/Maaser/Maaser Sheni/Maaser Ani.
Be'er Moshe (5:107:4) writes that while he thinks the Rash held the blessings would be Lehafrish Teruma/Terumat Maaser/Maaser/Maaser Sheni/Maaser Ani, he thinks the Rambam and Shulchan Arukh hold the blessings should be Lehafrish Teruma/Teruma/Maaser/Maaser/Maaser. Earlier (ibid. :2), he wrote that one separating multiple gifts but not all of them should adjust the plurals in the collective blessing to match what he is doing (eg. one separating just Terumah Gedolah, Maaser Rishon and Terumat Maaser would say Lehafrish Terumot uMaaser, while one separating only Maaser Rishon and Sheni and Terumat Maaser would say Lehafrish Terumah uMaaserot).
Sefer Eretz Yisrael (2:4:1) writes that the blessings would be Lehafrish Teruma/Terumat Maaser/Maaser/Maaser Sheni/Maaser Ani. (He implies that someone separating all but Terumat Maaser at once would maintain the plural form "Terumot" in the collective blessing.) Be'er Sarim 2:18 cites this approvingly.
Halachot, Halichot uMinhagei Eretz Yisrael by R' Chaim Luntul (p 75) writes that the blessings would be Lehafrish Teruma/Teruma/Maaser/Maaser/Maaser.
Acharit Hashanim (4:5:7) writes that the blessings would be Lehafrish Teruma/Terumat Maaser/Maaser Rishon/Maaser Sheni/Maaser Ani.
Rav Shlomo Zalman Aurebach (Maadanei Eretz Terumot 2:16:3) writes that the 5 blessings need to be different and specific. He is unsure if Terumat Maaser should be called "Terumat Maaser" or "Maaser Min HaMaaser". So his view is the blessings would be Lehafrish Teruma/(Terumat Maaser/Maaser Min HaMaaser)/Maaser Rishon/Maaser Sheni/Maaser Ani. (He implies like the Be'er Moshe above that plurals should be adjusted when making a collective blessing.)
The Arukh HaShulchan He'Atid (Terumot 59:11 and Maaserot 93:7) writes that the blessings would be Lehafrish Teruma (Gedolah*)/Terumat Maaser/Maaser Rishon/Maaser Sheni/Maaser Ani. (*It is unclear to me from his wording if he thinks the word Gedolah should be included in that blessing.)
The one time I had this question two LORs agreed that the blessing I should say before separating Maaser Sheni was "...Lehafrish Maaser Sheni."