I have the Shapton Glass stones in 1k, 3k, and 16k. My only Nani is a 150 brick (love that brick) but have used the other Nani's up to 10k.

I got the GS line due to price and space, hard to beat really. And they are good stones, I only use them for my kitchen knives now though, and tougher restoration straights.

Personally is cash and space where not an issue, I'd probably have gone with the Nani stones.