We've used the Gerber color changing cups and Playtex insulated cups for years, and they don't leak for us. It seems like they did sometimes leak when they were in the diaper bag, but we don't do that much anymore.
We used the Nuby ones and LOVED them, but the soft silicone tops eventually wore out. My sons liked to stick their fingers in the holes, which ripped them a tiny bit so they didn't seal anymore. And they liked to clamp them in their teeth to carry them around hands-free, which also ruined the holes.
Straw cups leak back out the straw because when the cup sits out for a while, the liquid and air inside of it warm up, increasing the internal pressure. That pushes the liquid up the straw. So when you see it starting to come back up, you either have to twist the lid off for a second to release the pressure, pinch the straw to let air in (works on some) or have your child take a sip.
The pressure problem can also cause leaking in regular cups, if they're upside down (like in a diaper bag), because the pressure builds up and can push juice out of the threads on the lid.
For your 7 year old, maybe get a sports cup. I haven't been able to get one for my 6 year old because they seem so expensive and we're unemployed right now. He only gets a sippy cup in the car. He just seems too old for it.
I now remember telling my boys that sippy cups are great because they don't spill when they ACCIDENTALLY get knocked over, but they're not totally leak proof, so please keep them upright. That has helped a lot since they were old enough to understand that.