I feel that 2003-2004 Kamen Rider Series installment Kamen Rider 555 did a significant break through with a more futuristic approach towards the appearance of its protagonist. Mecha was also introduced such as transforming the motorcycle into a sidekick robot. I really like the designs a lot and added a few of these vinyl figures under Hero Series toy-line together to other vinyl figure such as Ultraman and Power Ranger.
A few reasons why I settle for vinyl figures instead of more articulated ones are that I find awesomeness in vinyl figures like in terms of the 6" (10m) consistent sizing, it's made in a way how I grown up playing with and pricing of vinyl figures in Rider Hero Series remains very competitive till date (therefore it's relatively inexpensive to own one).
Slightly shorter standing besides the Green Ranger
Rider Hero Series Vinyl Auto Vajin figure can't transform however I do like its robustness, the sturdiness and I kind of feel that the proportionality is accurate to how the mecha appears on the series, considering the suit is donned by human actor and it has a bit of bulk.
Kamen Rider 555 (仮面ライダー555（ファイズ, officially Kamen Rider Faiz is the 13th installment in the Kamen Rider Series. The Smart Brain corporation, in pursuit of this, they develop three suits of power armour, called Rider Gear. Kamen Rider Faiz (仮面ライダーファイズ Kamen Raidā Faizu, Masked Rider Faiz) is the main protagonist of the 2003-2004 Kamen Rider Series installment Kamen Rider 555. Its gear is the first of the Rider Gears seen in the series. Its motif is based on the Greek letter phi (Φ).
Designated "SB-555V", the Auto Vajin is a transforming, artificially intelligent support mecha for Kamen Rider Faiz seen in the 2003 - 2004 Kamen Rider Series installment Kamen Rider 555. It is the first of the support mecha seen in the series, which can transform from a Smart Brain motorcycle (Vehicle Mode) into a flight capable robot (Battle Mode). Credits: Kamen Rider Wiki
Rider Hero Series is a soft vinyl figure series created by Bandai. The figures are very similar to Ultra Hero Series figures, with same articulation but different detail. The figures started release in 2000 and continuing today. The material is a soft vinyl figure. Some toys with molds of the Showa Riders and remolds of the Heisei Riders will be released with new name called "Legend Rider Series". It's released with a plastic and a Kamen Rider card is hanging on the back. Credits Bandai Wiki