To be economical get the biggest, sturdiest one you can find that will accommodate him when he's full grown. You're gonna have and use it for 10 to 12 years (more I hope), so invest in a good one now. I think my biggest one is 30" tall and around 42" long. Then partition it off while he's small. He should have just enough room to turn around and lay down. Too much room and he may decide to use one half as his bathroom.
I prefer the suitcase kind that folds for traveling or storage. Metal pan lasts longer than plastic. Two doors is nice, but unnecessary. A foam pad is nice if your dog doesn't chew it up, but totally unnecessary. After all, these dogs prefer the hard, cold bathroom tile to carpeting.
Mine (I have seven) do not have the drop pins in the corners. Less pieces to lose, that way. The big ones are heavy, but worth it. When he gets older and is trustworthy in a crate, you can always buy a light weight nylon travel crate. But if you do, don't get the kind with a curved top unless you like watching your dog roll downhill like a tumbleweed. They can turn those things over pretty easily.
When you get your wire crate, if the pan does not fit snugly in the bottom, lay a piece of pvc pipe at one end under the pan lip to prevent it from sliding around. Had one dog pinch his toes between the pan and the cage wires. He screamed like he was being murdered. Scared the pee waddin' out of me. Don't want that happening when you're away.
Get a fan to blow on him. Will help keep him cool and the white noise helps him sleep.
Hang a small stainless water bucket in one corner. You can use a carabiner or snap to clip it to the wires. Less chance of spilling or playing in the bucket that way.
That's all I can think of for now. Others will chime in.