Edit - hit that "post" button too fast
1. Terminator 2 - Judgment Day
I think this is probably his best work, though True Lies comes real close. It's also some of James Cameron's best work. This movie, while the time-travelling aspects might get problematic, certainly is tightly scripted, excellently paced, and even most of the CGI stands up well.
2. The Terminator
For having so little screentime in this movie there is a reason why Arnolds name is now associtated with it so intricately. You could almost forget that Linda Hamilton and Micheal Biehn were in it, or that it was written and directed by James Cameron. Arnold OWNED this movie. Without him there is no way it could EVER have become as iconic as it did.
3. True Lies
Definitely competes as Arnolds best work, though I think you have to give props to Jamie Lee Curtis, Tia Carrere, and Tom Arnold (maybe even Art Malik and Grant Heslov). It was a great ensemble cast. This movie REALLY deserved a sequel, or two...
4. Eraser
Not the best but I think it works. I think it showed signs that Arnold might have been getting back to his days of movies like Commando, Raw Deal, and Red Heat, but with a little more modern sensibility. James Caan also rocks.
5. Total Recall
High Concept stuff. A bit over the top but I don't love it any less. Another movie where the rest of the cast defintely helps sell it. Sharon Stone, Michael Ironside, and especially Ronny Cox who just does GREAT corporate villains with a gun: "I don't give you enough information to THINK! YOU do what you're told - THAT'S what you do."
6. Predator
Oh yeah the testosterone flows like wine but isn't that just what you get when you distill action movies down to their base components?
7. Commando
So much over-the-top action and UTTER insensibility to gratuitous violence. It's AWESOME, even if Vernon Wells' characterization of Bennett was quite lacking.
8. The Running Man
The cheesiest of Arnolds '80s blockbusters but if you take it in the spirit of its times it manages to stay in the top 10. Arnold was still at his best with the one-liners and it still had reasonably inventive action sequences. And how can you go wrong with Mick Fleetwood and Dweezil Zappa as your bit players?
9. Raw Deal
A formula movie that Arnold should have done even more of. He probably could have cranked out one like this every year and made as big an impact. It stays in the top 10 because it actually manages to eke out JUST a bit more personality for the character that Arnold plays than most any of his other movies. The rest of it is standard action movie.
10. Conan the Barbarian
Terminator and Conan are musts when doing a top 10 for Arnold. Despite it's many and sundry flaws and shortcomings it still needs to be listed. It could have been better, but all things considered it was better than it probably SHOULD have been - and I think Arnold deserves the credit for that.
That would be my top 10, but it would be "controversial" in that I actually haven't seen a few of his more well-known movies. The above includes only what I have seen. It should be noted that it becomes difficult selecting between the less stellar of his movies and many of those choices are then strictly a matter of personal taste as opposed to anything remotely approaching objective critique.
Terminator 3 - Rise of the Machines
A tedious, unfit conclusion to the series. It had it's moments but the whole thing was basically lifeless acting, dull plotting, and too far over the top.
The Last Action Hero
Not the best of his movies but not his worst by any means. It just comes off as too much of a one-joke premise. Worth watching mostly just for Charles Dance, not Arnold. But then there's also Mercedes Ruehl, Bridgitte Wilson, Robert Prosky, Anthony Quinn, Ian McKellan... I think it's adequate as parody but then should have been starring someone other than Arnold. As self-parody it's just a bit much. There's actually a decent action movie buried in there I think with all those aforementioned stars and it's that which enables me to watch it.
The 6th Day
Adequate, classical Arnold escapist action movie in the tradition of say, Red Heat and Commando. I just didn't think it had the same... panache as those.
Batman & Robin
Oh yeah, Arnold was in one of those, wasn't he? I couldn't really rank on Arnolds specific performance as the whole movie was a train wreck. That franchise was WELL off the rails.
End of Days
Jingle All the Way
Kindergarten Cop DVD
Pumping Iron (25th Anniversary Special Edition)
I've never actually seen ANY of these. People keep talking about Kindergarten Cop. I've seen one or two scenes. I won't be able to judge it at all though until I actually see the whole thing on cable. Neither of the other two I have much of any interest in so the only way I'll see them is if I'm really bored and there's nothing else on cable at that moment.
Collateral Damage
In the post 9-11 rush to sanitize movies I think this was one of those that suffered, if in no other way than by its release being delayed forever. Still, it was too slow paced for what one normally expects of an Arnold picture and it suffers in that regard as well. Again, with another star, and/or some script doctoring to liven it up it would have fared better.
Red Heat
Classic Arnold. Only fails to make the top 10 because, well, you gotta cut somewhere. Belushi actually makes this movie though. Arnold works well in it, but it's Belushi that cements this movie together.
Twins
Another one that has to be cut just for space. He and Danny Devito work well together. It just doesn't have the staying power to remain in my top 10. Still, it's amusing more than it is funny.
Junior DVD
Saw this movie once and that was enough. The premise just doesn't do a thing for me in the first place so all of the funny would be wasted on me anyway.
Conan the Destroyer
Lots of good moments here but Grace Jones and Wilt Chamberlain really drag this one down for me. I kinda went back and forth between this and Conan Vs. the Flower Children of Set, as to which deserved MORE to be cut. This one lost.
Red Sonja
Quite forgettable in every way. As Joe Bob Briggs said at the time, "Dino De Laurentis simply called him up and said, 'Arnold - please come save my movie!'"
Hercules in New York DVD
It can be AMUSING, but not funny, to watch because of how BAD it really is. It's a waste of BOTH Arnolds - Schwarzeneggar, and Arnold Stang (who belongs in movies of a more classic, wacky-caper caliber. Movies like It's a Mad Mad Mad Mad World. Or even doing voices for cartoons, but NOT this).