It's almost a moot point these days, since there's basically nothing new coming out in this scale. Most of the stuff available now is Chap Mei/Lanard stuff which are great for your kids but for the most part look low class next to Marauders/Joes/Bravo Team/What have you and would require obscene amounts of work to make into something that looks great. That basically makes the only viable option on the current market right now being Power Team Elite toys, which are a dieing breed as Big Lots weeds it out from its shelves, the price rises every year, and all the cool new stuff that isn't two decades old that M&C toys makes pretty much have to be imported directly from China.
However, most people here would make a solid argument that M&C toys isn't perfect because the stock paint work is awful, the figures though well articulated are cheap looking garbage that your kids should be strapping fireworks to, and of course their vehicles are under scaled. The larger the vehicle is suppose to be at scale, the more they will cheat proportions to make it look the part for a kid to play with. That said a lot of folks on here have done a lot with PTE stuff to make them look way better than they had any right to, so they make a great template for the talented and enthusiastic.
But yeah, the only thing that I'm a little loose on is construction equipment considering it comes in multiple sizes in real life. I'm also flexible on vehicles that there are no real life counterparts for. Sci-fi stuff for example.
