The only Spits that aren't absolute trainers are the Spit I and Spit V.
Ki84 is Japanese Spitfire. Rugged, super climb, uber flap trainer.
La7, D Pony, M jug, Temp, Dora, 4-Hog, K4*... qualify as easy mode. Fast and well armed, if you die in these planes more than rarely, you made a mistake somewhere, bad.
*K4, the only thing that makes a fair argument is the 30mm, but once you master that gun (or even just get decent with it) there are few planes in the game that the K4 cannot run down, out turn, and kill with ease. A well flown K4 with any altitude is just as dangerous as a Tempest or 262.
"Not easy mode?"
P-39's, P-40's, I-16
Yak 7, Spit and Hurri I, F4F, Emil slightly "less hard"
Not easy, but not hard: La5FN, Yaks 9 and 3, 109F and G, most 47's, 38's, and blue planes. B pony, Ki61
All that aside, the real determining factor on what is an easy mode and what plane is a pig? Aside from the pilot, which one of the two has the altitude and speed advantage. The low and slow Tempest/K4/Dora will get owned by the high, fast P39D, P-40C, or I-16 almost every time.