Solid top 3 op.
My favorites include: Silent Hill (technically Silent Hill 3 is the sequel to Silent Hill 1, but I can look past that given how good 2 was), Halo (including Halo 3: ODST because it's part of the same trilogy in timeline and gameplay), Metroid Prime (these are my favorites in the entire franchise along with fusion personally), Modern Warfare (i even liked Ghosts and Advanced Warfare so it should be noted I am by definition a cod fanboy...but to be honest the Modern Warfare series had my favorite campaigns and spec ops along with solid multiplayer....3 was horrible with lag compensation there's some things that make that my least favorite IW game for multiplayer https://www.youtube.com/watch?v=wJOpFCCnv0E, but overall it's still fun and had a good campaign), Ratchet and Clank trilogy (I thought the series went way downhill with deadlocked and later iterations, up your arsenal was actually my favorite), jak trilogy (first game being my favorite, 3 was a little down in terms of quality because it was too similar to 2 but it was still good), uncharted (don't own it, but i have played a bunch of it at college and i can see why people consider it so good) *off top of my head. comment may be poorly written and organized
tl;dr Silent Hill, Halo, Modern Warfare, Metroid Prime, Ratchet + Clank, Jak + Daxter, Uncharted, Mass Effect
Note: If we pretend Morrowind, Oblivion, and Skyrim is a trilogy it would be in my top 3.
