My only vastly different guitar is the DT-200 Destroyer. It's a hardtail with a big mahogany body and a 24 3/4" scale 22 fret neck with a fatter neck profile. I put in a Dimarzio Super Distortion in the bridge and a Humbucker from Hell in the neck spot. My thinking with this guitar is it's closer to a more classic rock / metal sound I think from the late 70's and early 80's.
The logic behind the RG's:
The RG3EXQM1: fixed bridge with a TZ bridge and PAF Pro neck. Cheap as hell guitar. My first fixed bridge too. Still plays great, loads more sustain, and reliable like Glen said on gigs being fixed bridge.
The RG570. The gold standard as far as I'm concerned. Bubinga striped super wizard. Original Edge. I'm not keen on pickup rings though. TZ - HS3 - PAF Pro pickups. I think she's going to need a refret soon though.
RG1570. I bought it as a modern "clone" to the RG570 but I like the direct mounted pickups. I might have sold this one off if the Edge Pro was still in production. I love this trem and like the thicker Prestige Wizard profile sometimes. TZ- Pro Track - Breed pickups. This and the RG570 I think are the closest I have to two guitars being exactly "alike."
RG550. Front routed. I can hear my picking "pop" better on a front route. Original Edge. Evo pickups. My only maple board too. I really dig maple boards too.
RG7321. The one with the Gibraltar style bridge. Blaze pickups. I like having at least one seven string. I miss having a trem seven though. If there's one guitar I could have back it would be the RG7620VK. Oh well....
And lastly the RG921. Great fixed bridge. I love the stock Dimarzio/IBZ pickups but I also bought a set of 36th Anniversary Dimarzios I've been going back and forth on putting in this one. If I had cash to throw away I'd get another RG921 or RG920 to put the 36ths in and leave this one stock but that kind of seems wasteful too. The 36ths would look awesome in it though and give the guitar more of a classic rock slant I think.
Anyway, that's how I see it. Lots of cheap guitars in my collection but I like the variety.