Should you still buy an Ubiquiti Edgerouter X in 2018? Is it still the best home router setup?

About ER-X's gigabit performance, I would note that the ER-X cannot do gigabit full duplex WAN. It can do gigabit up or down but not both at the same time. It will do 500/500 at the same time or 700/300 or whatever combination you can think of. (*I'll explain below) If you want your router to handle a 1000/1000 simultaneously on the WAN, then you need to get the Edgerouter Lite instead. Be warned though, ERL's CPU is slower than ER-X's, so if you want QoS or some other feature that disables hardware offload > ER-X is faster than ERL in those scenarios. 
 
As far as QoS goes, don't forget about bufferbloat. I'm using Smart Queue (fq_codel) for my 100/20 connection on my ER-X. I'm using it because I want to keep my connection as consistent as possible. I can hog basically all of my connection (fq_codel takes it's share of course) if I want (or need) to but the latency won't shoot up, it doesn't really budge much if at all. And if the missus happens to jump on on her system or some other device decides it needs to do it's update or whatever sync at that exact moment, then fq_codel will keep things fair. When talking of QoS, there's more to it than just basic QoS for reserving bandwidth for VoIP and stuff. And if you're into aqm algorithms and such, there's a compiled version of cake (yes, successor to CoDel/fq_codel is named cake) out there on the Ubnt community forums for Edgerouter devices. I haven't tried it on mine yet as fq_codel is working just fine for me. 
 
*The reason for this is the existence of the SFP version of the ER-X. The ER-X platform uses the Mediatek MT7621A SoC. Between the CPU and the switch block is a proprietary Ralink high speed bus which comprises of two 1Gbit/s links. Which means that this bus can handle 2Gbit/s aggregate.
 
 The switch block has 5x GbE ports as well as an optional RGMII interface. The ER-X-SFP uses this RGMII interface for it's SFP port. In the ER-X-SFP, one 1Gbit/s link goes to the 5x GbE ports while the other 1Gbit/s link fans out from the switch block and goes to the RGMII interface (SFP) On the ER-X however, one 1Gbit/s link goes to the 5x GbE ports just like on the -SFP but the other 1Gbit/s link isn't "connected" to anything. I can only guess that in the name of fairness and keeping things consistent, Ubnt decided to make the firmware as such that the ER-X and ER-X-SFP would perform the same in same situations/configurations. Hence the speed limitation.

I bought an Edgerouter X this year for my home, It does what we need we have a 300Mps down and 15Mbs up. Best $50 i have spent.

I bought an Edgerouter X this year for my home, It does what we need we have a 300Mps down and 15Mbs up. Best $50 i have spent.

Bought a Netgate sg-1000 in December; have wanted to play with pfsense for some time. Have had under 100 mbps so it worked fine. Now upgraded to gigabit fiber, so replaced with ER-X with hwnat.