Not sure if the switch will help you on the IOPS side, but if you want new.. Arista. For used I can highly recommend Mellanox. You can get SN2410's for around $ 1500 on ebay (if you're lucky) giving you 48x25 gbit plus 8x100 gbit, very low latency.
We've been running these in production for years now, no complaints whatsoever.