>>34293063I like 5's the most, with 7 and 6 being runner-ups.
7 is a mixed bag, having some of the best (UBs and Ultra) and worst (Dusk and Zeraora) to offer. 6 obviously wins in quantity and has some fairly good designs overall but I don't feel strongly enough about most of them to form a real opinion.
5 might not have much to offer and one design is a form with no in-game changes, but it has a lot of merit in repairing or improving the previous designs. It brings much needed new variety to the Kami Trio, the more mature look of Keldeo manages to build on/represent its lore/origin nicely without detracting too much from the original and the mascots are both very imposing, scary designs in terms of how they're forced fusions that really help set the tone for the game's plot and the nature of Ghetsis. Shame about how easy B/W Kyurem were to beat in-game.