Don't forget
cultivator's caravan and
daredevil dragster!
I've been playing with them in my new cube, and they've basically taken the role of equipment in that setting!
Smuggler's Copter: It's very strong, but it's strength does depend on how many 1-drops are in your cube, as you do need someone to crew it. If you can consistently jam it on T2 and leave it up to block, it's the most powerful of the vehicles. If you need to wait until T3 to have it 'active,' it's merely great.
Sky Skiff: A very strong card, and often underestimated.
Peacewalker colossus: I... ah, actually didn't play with this one... I really should.
Renegade Freighter: This has done a huge amount of work for me in the decks that I've ran it in. It's an aggressive card, but being able to have your 2-drop crush in for 5 trample damage in on T4 is great, and it only gets better with other buffs and effects. It's great for it's cost, and not so low-costed as to be busted.
Untethered Express: The +1/+1 counter effect wound up not mattering as much as I thought it would, as I typically used this as a top-end to highly aggressive decks, and either won or lost quickly after that.
Fleetwheel cruiser: One of my favorite vehicles, honestly. The fact that it comes in as a creature itself makes it a not-bad topdeck.
Ballista charger: I found this one to be rather lackluster, honestly. I prefer vehicles with either evasion, trample, or a similar effect. If you have a lot of X/1s in your cube it can be great, but it wasn't for me.
Skyship Sovereign: It's felt a little heavy for me, but the fact that it bolts on ETB saves it.
My top 3 vehicles for cube are:
1. Renegade Freighter
2. Fleetwheel Cruiser
3. Skysovereign, Consulate Flagship