well, it's not particularly fair to compare them, one is an enterprise switch that's $3000 new, and one is a mikrotik device that's $130 new. The Brocade was intended for enterprise and campus environments for the most part and wear items like onboard flash are duplicated for redundancy, the power supply is much higher quality (Delta onboard instead of a wall wart), a lot more ESD input protection on the physical ports/PHY (most of the mikrotik devices I've taken apart have NONE), the software and hardware has been QA'd quite a lot more (I know the ICX engineering & QA team at brocade on its own was larger than all of Mikrotik as a company) - if you want a general idea of Mikrotik's level of QA, read through some of the mikrotik megathreads here on STHI need 3-4 24 port switches with 10G uplinks. How does this compare to the Mikrotik 326-24G-2S+RM?
I was considering the Mikrotik because of price and quiet operation, but the ICX6450 are tempting. Could even get rid of some POE injectors by getting a POE version of the switch.
Aside from the obvious things above like hardware, they're also in different leagues software capability wise, the mikrotik is an l2 device only (no routing) while the 6450 is a full L3 router (at millions of packets per second & hundreds of gigabits per sec, not in CPU like some mikrotik models). However even comparing them for just L2 features, the mikrotik is still missing quite a few - no deep ACL's, no sflow, no stacking support, no QinQ, no out of band management, no 802.1X auth, no per vlan spanning tree, dynamic ARP inspection, no RADIUS/TACACS/TACACS+ authentication, etc etc, and that's just the L2 differences off the top of my head
The ICX6450 also has twice the 10gbE ports, which I'd imagine is the most important difference to most people on STH. If they were wildly different prices I would say to weigh your wants and needs to decide which to get, but given they're basically the same price thanks to ebay it's pretty much a no brainer