Which episodes should I watch if I want to get into MLP?

Start from the beginning.

• It gives you time for adjustment to character design. While animation in MLP is seamless and fluent most of the time you may be unaccustomed to animated creatures in general or this type of them.
• The series popularity derives from gentle character development, for me at least. I can say that I like everypony from Mane 6, because they all had some episodes focused on them.
• The show is partially chronological. All episodes opening/closing seasons were happening in their screening sequence.