I want a router like the Cisco that will have a fiber wan so I won't need the ISP's fiber modem/router.

I want a router like the Cisco that will have a fiber wan so I won't need the ISP's fiber modem/router.

In addition to what @doneware wrote: there are WAN technologies where one needs to be careful. One example is GPON where most networks use speciffic GPON ONT devices ... while there are GPON ONT devices in form of SFP, they might not be compatible with Routerboard devices and might require some special setup (by user, ISP or both) to make them work.

in general you don't have specificly LAN or WAN ports in routeros. those are just ports, and they act as you configure them. you can have all ports as wan if you wish so.

with regards if throughput: you can get 1Gbps pppoe+routing+nat with hex, hex-s, hap ac, hap ac2, 4011 and anything of the ccr series. (the bigger ccrs have fans, all the others are passively cooled)
if you need more ports (the first 3 have only 5-6 ports, 4011 has 11 ports and the ccrs vary from 8 to 16) i suggest you add just a small switch.
mikrotik offers a bunch of good devices for peanuts, and they can be all managed properly with cli and over a GUI, and are fanless. in terms of extra power consumption you get 24 wirespeed ge ports at 20-25W (crs125, crs326, ccs326). check here for switches:

https://mikrotik.com/products/group/switches ($140-$200)

and here for routers:

https://mikrotik.com/products/group/routers ($59-$1k)