Hi,
Sounds like you are about to choose your synths accordingly to your sequencer... not sure that's a good point: synths are musical instruments, seqs are basically tools; so I would say 1st go for a synth that fits your style and ears, then find how to make it sound.
That said, Mother 32 can give you a good taste of the moog sound; microbrute (not rackable) has a good voice with a good filter, fast LFO and a CV matrix bay for having fun with you BSP, you can also route audio in + some goodies and it goes for around 250E. If you are into cables and patchs a Korg Ms 20 rack could be an (expensive) option. And all of them are black!
I can understand about your elektron rytm feelings, but is a really good machine. Did you plug it in a decent PA+ sub system? And the elektron's clock man, plug a hotdog on it and it will be play in sync! CV and sample capabilities, audio in, class seq, 8 voices, memory, it's little and easy to fit in your rig, etc.
Minilogue could be nice. Poly + a keyboard that you could use to play other gear. Not sure that the key's size is a good option; if you really want to play keyboards then go for full sized keys.
Last I would say, if you are going for a full CV setup keep in mind that compatibility between aaanalog stuff such as voltages, resolution, clocking (and the BSP is a real piece of crap for that) needs time and understanding. For some people patching and syncing their gear represents 90% of their satisfaction, but doing some good music is really what you want isnt' it?
Use the 1500$ and keep your AR for a while!
So good luck and have a good time, buying gear is always a cool thig to do