why is merc better than fossil? (please, not a flame starter)

[Harry Putnam]

I've been using merc for a year or so, and like it fine.

Somewhere I read fossil is better for a small repo... so decided to
experment with it.  Seems good too. 

Before asking for guidance let me briefly explain my situation.

single usr host where this is happening
my HOST (Running Debian (jessie)) is on a smallish home lan
No commercial projects at all
No files that are terrribly valuable...
There are quite a few, though, that I would like to keep track of.

Very small potatoes but, since I run a variety of hosts (many are vms
I experiment with).  Means I have a fair number of system files and a
bunch of homeboy script to keep up with.

I'd like to hear a litte about the differences and worth of each from
some of the `old hands' here.