You need upload atleast 200kb/s for stable EU 40-50ms (ping).
Upload is more important than download in case of ping.
If you have network speed of 20MB/s and upload 5MB/s, if you download at full 20 the upload will suffer, vice versa. If you download at 13 you will have headroom for ping 5up+2down.
This is how I experienced the internet.
I hope I gave you the "friendly" answer.
As far for routers, 300mb/s (Megabits per second) is equal almost to 30MB/s (Megabytes per second)
10mbs (megabit) is equal to 1.024 MB/s or 1024KB/s.
Take the 300 one if you wont get higher speed internet in near future.
If im wrong, someone please correct me.
Thank you.
Just to add, you will have 20MB/s(roughly 200mb/s) download and 1.5MB/s(roughly 15mb/s) upload which is very good for home user.