When it comes to trukks vs. battlewagons, let's take a look at the pros and cons for holding melee troops.
Cons:
-Flimsy: Only
AV 10 means even bolters could glance them. Not super hard to destroy.
-Lack of space: You only get 12 seats, as opposed to a battlewagon's 20 seats.
Pros:
- Cheap: 35 points gets you a fast, open topped transport, with the reinforced ram and a gun, as opposed to the 115 points for a open topped transport with reinforced ram and no gun.
- Fast: Those extra six inches of flatting out help a lot when you've got to get in your opponent's face fast.
- Utility: Once your boys are out of the trukks, your opponent is tempted to ignore them, seeing as they're not that much of a threat. This is a mistake. Don't expect to out-shoot your opponent, but get creative and the trukk is very useful even when your boyz are out in the field. Use it to tank shock (ram required) your opponent off of an objective and steal it for yourself. Use it as mobile line of sight blocking terrain. Block guys from charging you. You never feel bad about suiciding a trukk for a greater purpose.
I vote for trukks, with the caveat that they work best if you've got some good line of sight blocking terrain to hide them behind so you don't get shot down turn one. I used to have a battlewagon in most all of my lists holding a boyz mob, warboss, and painboy. The problem I had with this is that the further up the field you go, the easier it is to kill that battlewagon. And when you got melee troops in there, you want to go up the field.
Honestly, when it comes to boyz, you get the mobs for the power klaws, especially if you're facing against high armor armies (ehem! Space marines. Ehem!). So stuffing them in a battlewagon gets you more boys, but boys attacks aren't the ones you're really counting on. And if you want to put somebody with a trukk, you can make it a min squad with a powerklaw nob (so 9 boyz, and 1 nob) and that gives you two seats in the trukk. You can stick a mega armor warboss in there for a perfectly filled trukk of death
That's my two cents anyways, trukks are just cheaper, faster, and perform similarly in survival when they get up close. Your metta may very.