They're are the kinds of signature instruments. They can all be awesome.
The first is a colorway or a configuration of an existing instrument. The glorious purple Reverend Linh Le is the most perfect example - a Reverend Dub King in a very flashy, distinctive colorway. Totally worth it too. I'd toss the Geddy Lee and the pink Road Worn Flea Bass into this category because they have clusters of features that actually existed together before in a previous era. I'd buy a decent example of a Road Worn Flea JB in a second, and I'm not even a fan.
Next is the modded guitars and basses that do something new, but still are exist as P-Basses, JBs, Strats, etc. The most successful version of this is probably a budget guitar - the J Mascis Jazzmaster, which put big frets, a tune-o-matic style bridge, and hot non-Jazzmaster-sounding pickups. They sold like crazy, and they were excellent to play if you wanted a reliable, aggressive sounding Jazzmaster. It was brilliant because it served the needs of actual current-day Jazzmaster users probably better than traditional Fender Jazzmasters did, although the pickups were a matter of controversy. The Jack Cassidy Epiphone is probably the equivalent bass - affordable, with individual features places in a modified existing design, although in this case it was that weird and rare semi-hollow Les Paul Bass. Those two are probably the most worth it of all signature models, at least for players who are inclined to like them.
Finally, there are the new-design signature models like the Reverend Wattplower, Fellowship, and Fatfish. I'd love to have a Mike Watt or Me'shelle Ndegeocello Reverend bass.