From a slightly different angle, the 2nd verse of Purple Haze has some mid speed picking that is worth getting down lest you become one of those people who can play fast but not slower.
Almost any Van Halen track is worth learning the rythm part, the bridge from Unchained is a particularly good lesson.
Truth. He was such a fantastic soloist that plenty of people don’t even realize what a brilliant rhythm player he was. Easily one of the all time great rock rhythm guitarists.
The intro and verses in Unchained are cool too, so is Panama and the lesser known “Can’t Get This Stuff No More” (that last one isn’t the coolest tune or anything, but the rhythm work is super creative.
Also, I found this rando Unchained tribute on soundslice 
I mean, if you’re not metal-adverse, and you want to develop a fast, efficient, and heavy picking hand, the entire Master of Puppets album is pretty much the gold standard.
After that, I’d toss out “Holy Wars,” and - while Schaeffer has pretty thoroughly torched his reputation thanks to a wee bit o’ violent insurrection, “Night of the Stormrider” was another album that my thrash guitarist friends always talked about as basically boot camp for thrash rhythm.
That said - there’s clearly a LOT more ways to be a great rhythm guitarist, than to be a great thrash guitarist.
Steamrock Fever from the Scorpions, downstrokes. Any Misfits or Ramones song, downstrokes. Do upstrokes too! 
Thieves and Liars from Ministry.
Pretty much any Sepultura song from Beneath the Remains or Arise.
Set the World Afire from Megadeth is a good one.
Never Die by Yngwie is tricky in all the right places.
Thanks folks, lots of good suggestions here.
The only Iced Earth song I have tried to play is Dracula. I find the heavy part hard to play at that tempo for the length of the song.
I found another one Europe - Scream Of Anger. Lots of 16th note picking and it is reasonably uptempo.
Lots of Iron Maiden…?
OK it’s still metal, but I’ve always found Solsagan by Finntroll to be quite the workout. If your tremolo picking is somewhat inefficient, you’ll know it very early into the song.
Question @aliendough. Is your stance on this “I don’t really like metal, what are some non-metal tunes to help me out” OR is it “I’m not familiar with metal but I know it’s got great rhythm playing. Any suggestions on some cool metal tunes I could learn”???
I assumed the former and it looks like others got that same vibe.
But reading your OP again I’m not so sure and maybe it’s the latter. Are you asking for metal tunes? I like just about any genre but I was in a band for about 7 years that was definitely metal. In my experience, the accuracy required for metal rhythm playing is unparalleled among any other genre I’ve dabbled in.
Just want to make sure we’re not missing out on an opportunity to throw some other tunes your way (though you may have enough at this point lol)
Bigfoot Alcatraz
Malmsteen has lots of good riffs.
I’m not familiar with metal, but I know it has good rhythm playing. As you say, it requires a lot of accuracy and makes it a good learning tool.
Cool, well if you’d like some stuff a good bit heavier than the others I’d suggested, this is one of my all time favs. Honestly, I became jaded with metal after the band thing I did years ago and I’d almost go so far as to say I now sort of hate metal lol! BUT…this song from KillSwitch is great. Pretty melodic and screaming is minimal. Awesome songwriting too.
Very fun rhythm parts! A nice mix of “chuggy” stuff (i.e. palm muted open strings) and moving octaves. Also, the chuggy stuff is brief enough that’s it’s a great opportunity to work on all down strokes, if you’d like.
@joebegly My theory is that everyone likes at least ONE Killswitch song, lol. This one has a great riff as well, also from that album!
At one point I had Rose of Sharyn as my ringtone 
Killswitch Engage… it’s like I’m back in my early-mid 20s. 
I was quite into a few of those New England area bands.
This was always my favorite KE tune:
I’m loving this selection, great song!
I bought the tabs for Cynic’s album Focus and there are some great rhythm parts too. It’s a great album too, if anyone hasn’t heard it.
@aliendough what tuning is your guitar in?
KSE is great and all, but you def need to be in drop C. I can think of others that are in E standard, or drop D.
The intro to holy wars by megadeth I’ve always found a struggle. Peddling on the low E a lot and striking out at other stings.
One thing I’ve learned is you have to relax a lot and delicately brush the strings to get an effortless motion going, the Amp is what does the work, not the force of your picking. Playing with the Amp loud and learning to control that or trying to play really quiet and soft but fast is a great way to get your nervous system to foucus better.
The angle of the pick is really important too, I play with a flat angle a lot, turning the pick more towards 90 degrees really lets it glide over the strings for that effortless motion.
I think sweeping is also a great exercise in flowing over the strings, tho I’m terrible at sweeping, but it is essentially the same angles as strumming or being effortless as you’re after.
The stamina really comes from relaxation rather than for example a runner building up their cardio and muscles. It’s all about stroking the strings softly and then you can move your hands for days.
I think thats also why alcohol is a preformance enhancer… to a point ofcourse. It connects you to your body better and lets you relax, once again to a point… I think alcohol is a bad thing. But it does work.
Bark at the moon is great, got that A string peddle with power chords. I find those type of rhythms a real challenge to control.
I think it also depends a lot on how you hold the pick, doing those peddles with three finger grip is way harder than just index because of the pick angle.
The intro to 5150 is also a difficult part. Van Halen - 5150 - YouTube
It’s got those hard double stops up the major chord and that has always tripped me up. Great intro to practice.
What you could do @aliendough is create an exercise for yourself that includes a sweep a strum and a single note picked line. In whatever combo you like, and try to get that up to speed, it should really force your hand to flow between each of those different picking motions and your body will adjust to it by nature.
I think it is mostly the up stroke that is holding many of us back, If you’re a downward pick slanter that is, so focusing on getting that smooth and loose is what will even you out. I find the up stroke is what catches me out on just about everything, sweeping, single lines, strumming…
Fight Fire with Fire helps incorporate power chords into your tremolo which allows you to play lots’a thrash stuff, this riff in particular:
