I agree with having post-game medal counts. I'm neutral on the site because both HaloWaypoint and Bungie.net are great sites.
However, I will heavily disagree on the playlists. There's no point in having social and ranked versions of the same modes. For starters, it's a waste of space. The second thing is that they'll play exactly same i.e. people playing intensely just to win. Calling something social doesn't mean people will say, "oh hey, I shouldn't put effort in this mode." As a result, you'll have uneven skill levels going head-to-head and will cause many people to complain about "tryhards" on the forums.
When it comes down to it, keep the normal competitive modes like Slayer, Breakout, CTF, Strongholds, Assault, and KotH in the Arena. Aside BTB, have the social aspect of Halo 5 be about custom modes i.e. an action sack playlist that features Grifball, Infection, Fiesta, Mongoose Sumo, and many more.
Example of how playlists should be ( * = social):
- Team Objective (no slayer or breakout; Has Strongholds, CTF, Assault, KotH)
- Team Slayer (Slayer and Breakout)
- FFA (more OBJ modes)
- SWAT (more OBJ modes)
- *BTB (still social)
- *Social Collection (Grifball, Infection, Fiesta, etc.)
- *Weekly Rotational Playlist