Pretty much above about what you like and can afford with time.
But something which i will echo from someone, if you do sparring, you can always use a different ruleset to your base style to adapt it a little bit/get used to differences. Like say if you did Judo and establish yourself decently in it to know the basics, you could then see if someone from it would have a sparring session using a different organizations rule-sets to see the contrast.
Personally that seems like a decent go between if you cant get to a style which interests you but can get to another grappling or striking style. So since you have done Wrestling, Judo might help your grappling more due to the slight differences in rules and tactics. But you could probably find some wrestling friends and use a judo rule set at home or something. Or spend less time as you said getting used to its rule set due to any possible similarities.
Because im a weapons nerd, i would say arnis, but thats just me.

(and depends on which organization and style)
organization/style of some of these would let anyone who has dealings with them echo their experiences. I would say pending arnis and hapkido style/organization, they do a pretty good blend of all ranges. From what i have seen/heard anyway.
Actually, grappling goes pretty well with weapons work due to the need of controlling the arm a weapon is in and so fourth.
So mirroring Christopher, Judo, HKD and arnis or a mixture of the 3 pending organization/style and if you like them would probably be the best.