I've been playing since Odyssey and my favorite set (by leaps and bounds) was the Kamigawa Block. Used to play modern but have since sold the majority of my collection for one thing or another (cough cough wife cough) and now play standard. What I enjoy about standard are not only the new mechanics that I have to learn to utilize but also the restrictions of the cards you can use. Yes there are a few cards in each set which are incredibly durable, adaptable and can be considered mainstream, looking at you Siege Rhino and yes some cards go CRAZY expensive Jace, Vryn's Prodigy  ^Flip but it also forces you to use a smaller set of cards and to create strategies around that instead of the tried and true approach (Splinter twin, elf weenie rush etc). I am also VERY partial to creating decks that are away from the mainstream. Not only are they unpredictable but they are almost always fun to play! Thank you all for your time and have a fantastic day!