Is there a way to sort my games by achievements?

Hi, you could try out AchievementStats.com or astats.nl and enter your profile ID
I'm not sure if one of these help you though, because both sites somehow are not working properly for me

Astats is down for me right now, but I copy/pasted data from the massive "Steam Games" page on AchievementStats into a Google sheet, and sorted it by number of achievements...
http://pastebin.com/86AMrism
(The second number after the game title is the achievement count, as reported by AchievementStats... no idea if it's accurate, but don't know why it wouldn't be. I excluded any games with zero reported achievements.)
[edit] Checked a few titles... most seem to be accurate, but Tales of Maj'Eyal apparently added another 300ish achievements that the site didn't have on record so... ymmv. [/edit]

For a more personalized list, you could have a look at the AchievementStats page's API, but you'll have to get familiar with some code writing then, too.

[edit]
Also, my favorite way to complete games is to go to my profile on steamdb.info, scroll down to my game list, and sort by the reviews.
It's a lot more satisfying than playing random crap games just trying to get their achievements.
[/edit]

Try truesteamachievements.com

I would recommend looking into Backlog Assassins group, they have a wonderful website that has tools like this. I use it myself and find it to be very helpful and especially motivating to help with my backlog!

https://www.steamgifts.com/discussion/b9XQO/extraordinary-backlog-assassins-wanted-apply-here-blaeo-thread

not trying to create a ruckus, but that seems like a horrible way to do things. Some games give you an achievement just for starting a new game, whereas other games are much more stingy, like requiring you to complete a huge chunk before you get one.

But I guess it's as good a method for attacking the backlog as any.

You can use https://achievements.justarchi.net/

created by JustArchi (https://www.steamgifts.com/user/JustArchi)

All good suggestions, thanks. Obviously, I'm going to be a bit more discerning in what games I play, just looking for someplace to begin.

In this case I'd recommend my own tool - it does exactly what you're asking for. Example.