If you just want to play to win, play SM. They are cheesier then the whole state of Wisconsin (where cheese is cheese, no offense intended to citizens of Wisconsin).
I think everyone plays to win, at some level. It might not be your primary goal, but everyone prefers it to losing, all other things being equal. You can cheese out SM, but so can you cheese out
almost anything else. Orks used to be one of the armies that you maybe couldn't fully powergame with. Now, I think you
can powergame with them, if you want. But of course, as with other armies, including SM and Eldar, you don't
have to take a power list.
But what is the power Ork list? Well, I'd speculate right now that it's probably an enormous horde of Boyz. Slugga and Shoota are both good, and I think some mix is probably ideal. But the most broken thing in the new book is probably plain ol' Boyz, just because they're so absurdly cheap. There are still some arguable points though, such as whether 20 or 30 is the best unit size, and whether Shoota Boyz should ever have rokkits or Slugga Boyz should ever have big shootas. In the end, I think if you take a really huge number of them, and they aren't in squads of less than 20, you'll have some game.
On the other hand, because they are so cheap, you can take mobs of 12 Boyz in trukks and still field a LOT of them, and give your opponent really too many trukks to kill easily, so that may be a viable option for a super-competitive list too.
Then, though, they need to be supported, and there is a lot more room for debate there too. A lot of people were really excited about Zagstrukk, for example, but I haven't heard a great lot of praise for him since the codex has been released. You can take a bunch of Kans and some Dreads, or you can take Lootas and Big Gunz. You can take Weirboyz for extra Waaagh!s or Big Meks to give advancing Boyz a cover save. You can put a Warboss on a bike and tool him up, and have a combat monster comparable to a winged Hive Tyrant or a Daemon Prince. I think that all those options are very powerful, though some are better in certain situations. There seem to be almost too many good choices for Orks right now.
I suppose in very general terms, the supporting units for a footslogging horde of Orks should either tie up enemy shooting units early in the game or be good at killing enemy vehicles, and so have some mixture of speed, anti-armor capability, and close combat ability (though not necessarily all three). But that encompasses so many Ork choices that it doesn't help a lot in deciding how to build an army, in terms of the finer details.
It will certainly take someone better at this game than I am, and more purely dedicated to winning, to come up with a totally optimized Ork list. In the meantime, I'll take something that can win at the level at which people play in my local games store, and that includes models I like, and be happy with it.
