[Blade Raider]

New? Sales are best. HLJ has Kamen Rider sales from time to time with some rather good deals on most of the lines they make. The simple way is to just say that Figuarts are the standard for collectors (with good reason), but there's plenty of choices to choose from.

The best way it by process of elimination. What's important to you? Articulation, scale, price, gimmicks, detail, character selection, etc?

Articulation:
For articulation, there is no better than Figuarts. Figmas, SIC Kiwami Tamashii, SIC, and main yearly Rider line (like the FMCS line Paladin meantioned) are all very well Articulated, they just can't top Figuarts.

Scale:
SIC Kiwami Tamashii are close to 4.5" tall and work well with today's GI Joe (There's also older lines in this size called Motion Revive, but the prices are insane).

Figuarts, Figmas, and the main yearly Rider line are about 6" and fit in with Marvel Legends, DCUC, etc. This is the most popular scale for Riders.

SICs dwarfs the rest of them. I think they're about 7-8" tall.

Price:
For the cheapest bang for the buck, there's the SIC Kiwami Tamashii line that costs about $10-$15 a figure. The secondary market on these aren't to bad, if not cheaper sometimes.

The main Rider line normally costs about $20 each. The secondary market prices aren't bad if you can find them.

Figuarts are at least $35+, though if you wait for a good sale, you might be able to get some for less than $20. On the other hand, if you want a specific rider that was made a couple of years ago, it can get really pricy really quckly. And don't get me started on the exclusives.

Figmas can be the cheap alternative to Figuarts if you're into Ryuki designs. At one point, many of them were down to $7 each. It also probably going to be the only way to get a good non-exclusive Siren/Femme.

SIC are pricy, normally more than Figuarts, but not by that much. Shipping might be more due to size as well.

Gimmicks:
This is where the main yearly line excels. Things like W and OOOs being able to mix and match the parts to make their different forms. Kabuto can cast off. Decade's figures can transform into their Final Form Ride. And so on and so on.

Figuarts has the gimmicks, but only for show. Form changes require buying another figure.

SIC does the gimmicks of the main line, but there's an insane amout of part forming.

Detail:
SIC/SIC KT are all reimagined Kamen Riders while Figuarts, Figmas, main lines, etc are made to look like the suits. SIC/SIC KTs are great if you like the reimagined designs. If you'd rather have the suits, Figuarts again tends to be the thing to go for.

Figuarts trys to get the details as close to the show as possible while having paint apps for as much as they can. SIC/SIC KT are the same, but redesigned in it's own style and tends to be more about sculpted details for the sake of sculpted details.

Figuarts and SIC/SIC KTs both have compound eyes where the eyes have clear plastic domes over detailed eyes underneath. This makes for much more pleasing heads to look at. Meanwhile, the other lines normally just have simple painted eyes that can look boring sometimes.

Character Selection:
The big one. Afterall, we all have are favorite Riders and if they don't make the one you want in one line or another then it eliminates that line from the choices and possibly even open new doors to discontinued lines.

And I haven't even touched things like vinyl (which I honestly don't know what the appeal is), candy toys (miniplas and the like), or Real Action Heroes (pricy 12" figures that even make the actors sometimes).