Buying used I'd suggest Yamaha, Sire, Ibanez, some Squier stuff
I bought back an Ibanez ATK700 last week that I sold 2 years ago. Really abused but 100% functional and a WICKED Musicman-esque bass. £120 and I could have got it cheaper but the seller was a work colleague. Nearly leaves enough in the budget for a used Ashdown ABM500, which can only be good...
My number one is currently wearing Ernie Ball Cobalts, which I like A LOT.
Really liked the D'addarios that came fitted on my Sire 5 (only my 2nd experience of D'addarios on bass) so I'd like to give the NYXLs a shot. "deep, powerful lows, focused punch and accentuated harmonics"? Focused punch sounds right up my street!
Traded my Ibanez SRC6 for Ade's Squier CV P. Ade was great to deal with, and he really stepped up when parcelforce managed to mangle the Squier during transport. Ade immediately offered either a trade reversal or to compensate me for the damage, no questions asked. Couldn't ask for a better response to the situation really!
I may be talking out my hat (if I was wearing one) but surely the most obvious place to put the front strap button is as close to the headstock as possible while still on the body, and move the rear strap button away from the bottom edge to change the pivot point? See Dingwall Dbird as an example:
I suppose it depends on where/how you want the bass to hang though. The only experience I have with anything vaguely thunderbird esque is my Tokai Thunderbird. First fret position feels MILES away so I'll be trying this if I ever get round to refurbing the beast...
It'll still be quite dark though. I suppose it depends what the OP means by 'modern'. Josh Broughton was kind enough to share some tips with me about how to brighten up my own blueberry, but I made so many changes I have no point of reference now, so I'm planning on building at least one other for comparison.
@ben4343 mentioned the nature control. On mine it's a little hard to use. A tiny change makes a huge difference. I'd planned on swapping it out for a smaller value and adding a few padding trimmers to allow me to zone in on the section of the dial I would use most, if that makes sense.
Broughton Azure drive springs to mind.
You could have one of the fx builders here build you a BBBOD clone with a few mods to brighten it up. The fuzz dog juicy blue kit is excellent.
I don't think it's just high... It seems to be running WAY off the side of the neck... Look at the 2nd to last picture. You shouldn't be able to see the string from the back!
The lines are kind of blurred now since the ABZ now is similar to what AB1 USED to be. Body wood, finishes and fancy top options seem to be the biggest difference between those 2.
AB2 is different neck and body woods, semi hollow.
The Combustion came before the NG2, and are what the NG2 is based on. Pickup locations, preamps and colours are the differences there.
Never played any Dingwalls other than the 2 AB1s I owned. Both brilliant basses. Don't think you can really go wrong with any of them. I'd love another some day...